Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Sat, 10 Aug 2002 07:04:00 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Sat, 10 Aug 2002 06:51:05 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: OLTC X-Mailing-List: archive/latest/667 X-Loop: tesla@pupman.com Original poster: "Mr Gregory Peters by way of Terry Fritz " Terry, I must say that I just cannot wait to see if your OLTC works! I'm probably more excited about it than you are :) It's good to see someone actually trying an idea out, rather than dismissing it as impossible at the theorising phase. I wish you all the best in your conquest. I am/was currently designing and collecting parts for a solid state CW coil, but I'm going to hold off for the moment, and see how your OLTC works - if it does, your system will be cloned in no time :) Good luck and best wishes, Greg Peters Department of Earth Sciences, University of Queensland, Australia Phone: 0402 841 677 http://www.geocities.com/gregjpeters Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Sat, 10 Aug 2002 08:56:24 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Sat, 10 Aug 2002 07:41:14 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: Re: OLTC X-Mailing-List: archive/latest/686 X-Loop: tesla@pupman.com Original poster: "by way of Terry Fritz " In a message dated 8/10/02 6:01:58 AM Pacific Daylight Time, tesla@pupman.com writes: << Terry, I must say that I just cannot wait to see if your OLTC works! >> Hey Terry, I'm going to have to show my ignorance and ask what the "OL" in OLTC stands for? I have started following this thread with in- terest but can't recall what the "OL" stands for for :-/ David Rieben Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Sat, 10 Aug 2002 08:54:47 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Sat, 10 Aug 2002 08:48:04 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: Re: OLTC X-Mailing-List: archive/latest/685 X-Loop: tesla@pupman.com Original poster: "Terry Fritz" Hi David, At 09:16 AM 8/10/2002 -0400, you wrote: > >Hey Terry, > >I'm going to have to show my ignorance and ask what the "OL" >in OLTC stands for? I have started following this thread with in- >terest but can't recall what the "OL" stands for for :-/ > >David Rieben > No worries, if this works, that question may get asked again someday :o)))) It stands for "Off-Line". This coil runs right 'off line' voltage AC without step up transformers. The primary circuit is not 10,000 to 20,000 volts like in a conventional coil but rather about 500 volts resonated up from the 240 VAC line voltage. http://hot-streamer.com/temp/OLTC8-8-01.gif (BTW - I think hot-streamer.com will be working much better now ;-)) In this diagram (a littles sketchy I guess, prolly should make a nice one...) the top two circles are the AC line voltage like from a dryer outlet. 120 - 0 - 120 split single phase. That voltage is simply rectified with a bridge rectifier and feed through the inductors to C7 which is the main primary cap. It is like 28uF in this case since the voltage is only about 500 volts. The switch in the lower left is an IGBT array in real life that can switch the 500 volts with very low loss (2500 amps!). The rest of the coil is conventional but the primary is only a single big turn and the secondary has many more turns since the operating frequency is lower. This shows the main waveforms: http://hot-streamer.com/temp/OLTC-08-07-1.gif The green is the AC from the rectifiers, the red is the voltage on the main cap, and the blue is 100X the charging current. The advantage is that there are no transformers, variacs, PFC caps... I am trying to get the entire system (control cabinet, and coil, to weigh very little, like 30 pounds) The main gap is solid state and eliminates the giant loss of a conventional spark gap. Therefor, if this coil has 700 watts input, that is easily equivalent to a 1kW+ conventional coil. If the power is scaled up, there is very little additional weight. I think such a system could do 7 foot arcs if the cap and IGBT array are beefed up to take about 5000 amps peak. But that is all one would have to do. There really is just not much "stuff" to such a coil and the theory is actually simpler but "new". Right now, it is just all theory and computer models but I am trying to build it up to see if it really works. It really "has" to work. It just a matter of getting components to do what the models says they have to do. Modern caps and IGBTs seem to be very capable of the task. I should make a nice web page and explain all the details in a nice format. But I could spend my time doing that or building the coil. So... this is all you get :o)) I have kept and reported all the details to the list if you sort for posts beginning with "OLTC". BTW - Some of us remember the days when people said computers could never predict a Tesla coil's functioning (and you know who you are! :o)))). Now it seems we can't build Tesla coils without them ;-)) LTR coils were first predicted by computer, but we would have figured it out fairly quickly without them. Computers certainly figured out the best component values for them far faster than say "trial and error..." However, this OLTC thing would have been virtually impossible to "whip up" without a LOT of computer power. There are some pretty tight regions it needs to work in and specs it has to meet to operate. One could never figure out how to get every thing to "sing" together without lots of study by computer. Also, many of the ideas that make it work, where from others here on the list. I sort of had the idea, but great ideas from many people could be quickly gathered here that really provided the set of keys to make it run. On-line data sheets and parts ordering saves a few months too :-)) If this works, it will truly be a modern state of the art Tesla coil that will be very new and different. It may also be far better in many ways. If we can get it at 30 pounds, keep it simple, $400, and seven foot sparks... It would "change things"... Cheers, Terry Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Fri, 16 Aug 2002 08:20:00 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Fri, 16 Aug 2002 08:09:29 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: RE: OLTC X-Mailing-List: archive/latest/1094 X-Loop: tesla@pupman.com Original poster: "Dan Kline by way of Terry Fritz " Hi Terry, I forwarded the OLTC info to an engineer-friend of mine who talked about building this sort of thing a lot over the last few years. He had a comment about the design and asked me to forward his email on to the list. Dan Kline ----- Hey, I looked at the OLTC. Really cool idea! If he gets things working, He should be able to deliver about 1300V to the primary coil! I spotted something important that Terry appears to have overlooked, however. He should place a FAST recovery diode (1kV) reversed biased from the 150mH coil to the minus return of the DC input (Cathode would go to the 150mH coil side opposite the 47uF cap and the anode goes to the minus DC return). WHY? Let's say that current to the 150mH coil is switched on and continues to flow until the 47uF cap is fully charged to the DC input level (240V*1.41*2=677V). The coil current will be max at this point. You can still leave the switch on and the 47uF cap will continue to charge to a voltage greater than the DC input because the coil field is collapsing and will source extra voltage to charge the 47uF cap. This will continue until the coil current is zero, corresponding to the max voltage on the 47uF cap (theoretically 2*Vin or 1350V) This is resonant rise. You can open the switch at this point and take the 1350V on 47uF, or you can leave the switch closed and the 47uF cap will ring with the 150mH coil until eventually the 47uF cap reaches the level of the DC input (677V). With the current monitor Terry has integrated into his design, my guess is that he wants the 1350V level on the 47uF cap. This requires that he open the charging switch at precisely the moment when the 150mH coil current is zero. In the real world he can get close, but there will likely still be a little bit of current flowing when he opens the switch to take the 1350V charge on the 47uF cap. HERE IS WHY YOU NEED THE FAST DIODE: When the switch is opened while current is flowing in the 150mH coil, the collapsing field will generated as much voltage as it can to try to continue the current flow. This will over-voltage the IGBT switch and cause its destruction! PREVENT IT> Add the FAST recovery diode (like an International Rectifier brand; irf.com) as previously described to provide a current path for the 150mH coil when the switch is opened. I have learned this the hard way in high power inductive switchers. It's late and I'm harping. I just don't want him to get discouraged when his IGBT explodes. He has a very good idea and it is not too complex to build. I hope he gets 4 foot white hot bolts! Perhaps you could forward my comments to the list? -Brian Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Fri, 16 Aug 2002 13:14:05 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Fri, 16 Aug 2002 13:07:19 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: RE: OLTC X-Mailing-List: archive/latest/1109 X-Loop: tesla@pupman.com Original poster: "Terry Fritz" Hi Dan, You may want to pass this on to your friend. He is pretty sharp :-)) >Hi Terry, >I forwarded the OLTC info to an engineer-friend of mine who talked about >building this sort of thing a lot over the last few years. He had a comment >about the design and asked me to forward his email >on to the list. > >Dan Kline > >----- > >Hey, > >I looked at the OLTC. Really cool idea! If he gets things working, He should >be able to deliver about 1300V to the primary coil! I "think" the theoretical limit is 677V. 240V*1.41*2=677V >I spotted something >important that Terry appears to have overlooked, however. He should place a >FAST recovery diode (1kV) reversed biased from the 150mH coil to the minus >return of the DC input (Cathode would go to the 150mH coil side opposite the >47uF cap and the anode goes to the minus DC return). > >WHY? Let's say that current to the 150mH coil is switched on and continues >to flow until the 47uF cap is fully charged to the DC input level >(240V*1.41*2=677V). The coil current will be max at this point. You can >still leave the switch on and the 47uF cap will continue to charge to a >voltage greater than the DC input because the coil field is collapsing and >will source extra voltage to charge the 47uF cap. This will continue until >the coil current is zero, corresponding to the max voltage on the 47uF cap >(theoretically 2*Vin or 1350V) This is resonant rise. You can open the >switch at this point and take the 1350V on 47uF, or you can leave the switch >closed and the 47uF cap will ring with the 150mH coil until eventually the >47uF cap reaches the level of the DC input (677V). With the current monitor >Terry has integrated into his design, my guess is that he wants the 1350V >level on the 47uF cap. This requires that he open the charging switch at >precisely the moment when the 150mH coil current is zero. In the real world >he can get close, but there will likely still be a little bit of current >flowing when he opens the switch to take the 1350V charge on the 47uF cap. >HERE IS WHY YOU NEED THE FAST DIODE: When the switch is opened while current >is flowing in the 150mH coil, the collapsing field will generated as much >voltage as it can to try to continue the current flow. This will >over-voltage the IGBT switch and cause its destruction! PREVENT IT> Add the >FAST recovery diode (like an International Rectifier brand; irf.com) as >previously described to provide a current path for the 150mH coil when the >switch is opened. I have learned this the hard way in high power inductive >switchers. Voltage spikes like this are generated across the inductor when the IGBTs fire. http://hot-streamer.com/temp/OLTC08-16-01.gif I don't think a diode will work since the voltage spike is in the 'same direction' as the normal voltage on the inductor in this case. The IGBTs are protected by the 47uF cap so it never gets to them, the danger is to the other side of the inductor. The voltage spikes are not too terrible considering the bridge rectifier is 1000PIV. there are MOVs there at 700V but best not to depend on them for other than 'emergency' duty. But the solution should be simple and it is on the detailed diagram: http://hot-streamer.com/temp/OLTC08-16-03.gif Just two little caps keep a current path for the inductors and reduce and control the high voltage spikes: http://hot-streamer.com/temp/OLTC08-16-02.gif http://hot-streamer.com/temp/OLTC08-16-04.gif There are still big spikes, but they are well within the system's ability to handle. It is hard to get rid of them without making something hot. So I 'think' I have it figured out ;-) If the primary voltage really should be 1350V, I would like to know about it :-)) Thanks for the insight ;-)) Cheers, Terry > >It's late and I'm harping. I just don't want him to get discouraged when his >IGBT explodes. He has a very good idea and it is not too complex to build. I >hope he gets 4 foot white hot bolts! > >Perhaps you could forward my comments to the list? > >-Brian > Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Sun, 18 Aug 2002 01:21:01 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Sun, 18 Aug 2002 01:17:49 -0600 From: "Tesla list" To: "Sean Taylor" Cc: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: Re: OLTC X-Mailing-List: archive/latest/1227 X-Loop: tesla@pupman.com Original poster: "Terry Fritz" Hi Sean, A good and vital question, Easy to answer... http://hot-streamer.com/temp/irg4pf50wd.pdf The IGBTs have two die in them, the IGBT itself, and one big honk'n ol' high-teck HEXFRED diode in the reverse direction ("co-pack" since the TO-247 package contains two devices). It will take the full IGBT load in the reverse direction with ease. Since the coil is basically DC, the big reverse diode only comes into play during the reverse direction of the firing ringdown. I first heard of this idea from Antonio. IGBTs (and HEXFRED diodes) also have one vital characteristic. Unlike FETs that "look like" resistors when on, IGBTS look like diodes when on. I.e. they only drop like 5 volts at 200 amps! So 1000 watts peak loss... A good FET with 0.5 ohm loss at 200 amps looses 20,000 watts (100 volts)! This is the neat thing about IGBTs, they can conduct giant currents with very low voltage drop and very low loss. Pole pig systems are "old", OLTC systems are "bleeding edge"... Lots and lots of nice pole systems... Zero OLTC systems... Of course, there was a day when that was true of MMCs too, and suddenly oil/poly caps became extinct... Exciting isn't it ;-))) Cheers, Terry BTW - I'll copy the list on this since it is a basic good question that others must be wondering.. At 11:45 PM 8/17/2002 -0700, you wrote: >Here's a question for you Terry . . . > >I don't know a whole lot about IGBTs, but from what I understand, they're >basically a BJT, but have an insulated gate (IGbt, duh . . .) like a FET, so >very little (next to none) current into the gate at DC. However, (here >comes the question) aren't IGBTs "one-way" devices? I.E. Won't they conduct >current in only one direction? When the ringdown occurs, current will try >to flow in both directions of course. Are the intrinsic diodes taking care >of this? What am I missing in the OLTC? Maybe I should have posted this to >the list, rather than bother you, and take you away from working on it :-) >Anyway, hope it goes well, I'm excited to see this thing work, except that I >was looking forward to get a pig system running, now I don't know if I >should spend the money on one! :-) > >Sean Taylor > Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Sun, 25 Aug 2002 10:47:42 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Sun, 25 Aug 2002 10:36:49 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: OLTC X-Mailing-List: archive/latest/1505 X-Loop: tesla@pupman.com Original poster: "Gregory Peters by way of Terry Fritz " Terry, congratulations! A good way to prevent arcing between the primary and secondary, should this prove to be a problem, is a couple of layers of 0.060" LDPE sheet. Congratulations and well done. Can't wait for the full power tests! Cheers, Greg. Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Mon, 26 Aug 2002 12:35:49 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Mon, 26 Aug 2002 12:19:48 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: OLTC X-Mailing-List: archive/latest/1557 X-Loop: tesla@pupman.com Original poster: "David Huffman by way of Terry Fritz " Terry, you are the man! Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Tue, 26 Nov 2002 09:14:15 -0700 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Tue, 26 Nov 2002 09:01:58 -0700 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Version 5.1.1 Subject: OLTC X-Mailing-List: archive/latest/5761 X-Loop: tesla@pupman.com Original poster: "Brett Miller by way of Terry Fritz " So Terry, Have you been doing any work on the OLTC project lately? -Brett _ Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Tue, 26 Nov 2002 09:14:11 -0700 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Tue, 26 Nov 2002 09:04:28 -0700 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Version 5.1.1 Subject: Re: OLTC X-MIME-Autoconverted: from quoted-printable to 8bit by poodle.pupman.com id JAA21805 X-Mailing-List: archive/latest/5762 X-Loop: tesla@pupman.com Original poster: "Terry Fritz" Hi Brett, I have been involved with too many other projects lately so not much new work has been done. It is also too late in the year now to work outdoors with bringing it up to 240 VAC input. It will probably be on hold till spring Cheers, Terry At 06:13 PM 11/25/2002 -0800, you wrote: >So Terry, > >Have you been doing any work on the OLTC project >lately? > >-Brett > >__________________________________________________ >Do you Yahoo!? >Yahoo! Mail Plus ­ Powerful. Affordable. Sign up now. >http://mailplus.yahoo.com Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Sat, 17 Aug 2002 10:57:14 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Sat, 17 Aug 2002 10:47:15 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: OLTC (was Fwd: Hmmm...) X-Mailing-List: archive/latest/1164 X-Loop: tesla@pupman.com Original poster: "mrpaslow by way of Terry Fritz " Hi Terry, Here's more from Brian. Dan Kline > Subject: Geez... > Date: Sat, 17 Aug 2002 01:47:16 -0400 > > Hey, > > I am a dope. Since it was 3AM I neglected to do any > math on Terry's power supply. I was only referring > to the first stage of the setup, where he charges up > the 47uF cap. Even though he may not get 1300V on > the 47uF cap, If he opens the IGBT while the 150mH > coil is charging, the inductor becomes the source, > and its polarity reverses. This will place a greatly > negative potential on the end of the coil connected > to the IGBT, so that the total voltage across the > IGBT consists of DCin - Vc + V(150mH). It is the > voltage kick from interrupting the coil that is the > problem, which works out to overvoltage the IGBT > unless you provide an alternate current path for the > kick pulse. Hence the afforementioned diode of my > last post... > > Depending on the type of IGBT you have, it may have > some built in body diodes which will clamp a few > millijoules of inductive energy before overheating > the die. It's OK for an occasional surge, but not > for repetitive abuse. > > For some reason I cannot get a clear pic of the > schematic, so I am working a bit in the dark. Is the > IGBT in the first section ONLY used to turn on the > supply, then stays on until the ozone fills the room > and it is time to go out for a cig? If it is only an > on switch, then why not just use a triac on the AC > input side of the bridge? Is is a lot less to worry > about just to turn the thing on (but it must stay on > until the 60HZ half cycle is complete). There are > also optoisolators with small triacs that can be > used to trigger the larger power triac (the ON > switch). > > Or, is the supply turned on just long enough to > charge the 47uF cap, then the supply is turned off, > then the 47uF cap is discharged into the primary of > the output coil, then the cycle repeats again by > turning on the supply to again charge the 47uF cap? > If this is the duty, I can see why you would want an > IGBT for the power switch. > > This is a very novel idea which I would like to > learn more about. Has someone posted an article on > the operational theory behind this setup? I am > throwing out a lot of guesses and think it's time > for me to hush until I learn more. :) > > -Brian > > Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Sat, 17 Aug 2002 13:13:11 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Sat, 17 Aug 2002 13:08:35 -0600 From: "Tesla list" To: tesla@pupman.com Cc: "B" X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: Re: OLTC (was Fwd: Hmmm...) X-Mailing-List: archive/latest/1176 X-Loop: tesla@pupman.com Original poster: "Terry Fritz" Hi Brian, At 08:30 AM 8/17/2002 -0700, you wrote: >> Subject: Geez... >> Date: Sat, 17 Aug 2002 01:47:16 -0400 >> >> Hey, >> >> I am a dope. Since it was 3AM I neglected to do any >> math on Terry's power supply. I was only referring >> to the first stage of the setup, where he charges up >> the 47uF cap. Even though he may not get 1300V on >> the 47uF cap, If he opens the IGBT while the 150mH >> coil is charging, the inductor becomes the source, >> and its polarity reverses. This will place a greatly >> negative potential on the end of the coil connected >> to the IGBT, so that the total voltage across the >> IGBT consists of DCin - Vc + V(150mH). It is the >> voltage kick from interrupting the coil that is the >> problem, which works out to overvoltage the IGBT >> unless you provide an alternate current path for the >> kick pulse. Hence the afforementioned diode of my >> last post... There may indeed be better resonant modes and such that could be used. In this case, I just picked the easy one ;-) Also voltage doublers may be possible: http://hot-streamer.com/temp/ON-LINEVoltageDoubler.jpg >> >> Depending on the type of IGBT you have, it may have >> some built in body diodes which will clamp a few >> millijoules of inductive energy before overheating >> the die. It's OK for an occasional surge, but not >> for repetitive abuse. They have big beefy 200 amp HEXFRED diodes in the reverse direction. http://hot-streamer.com/temp/irg4pf50wd.pdf >> >> For some reason I cannot get a clear pic of the >> schematic, so I am working a bit in the dark. Is the >> IGBT in the first section ONLY used to turn on the >> supply, then stays on until the ozone fills the room >> and it is time to go out for a cig? If it is only an >> on switch, then why not just use a triac on the AC >> input side of the bridge? Is is a lot less to worry >> about just to turn the thing on (but it must stay on >> until the 60HZ half cycle is complete). There are >> also optoisolators with small triacs that can be >> used to trigger the larger power triac (the ON >> switch). >> >> Or, is the supply turned on just long enough to >> charge the 47uF cap, then the supply is turned off, >> then the 47uF cap is discharged into the primary of >> the output coil, then the cycle repeats again by >> turning on the supply to again charge the 47uF cap? >> If this is the duty, I can see why you would want an >> IGBT for the power switch. The IGBT array performs the same function as the spark gap. The array turns on for about 100uS every 8.333mS This completes the primary LC circuit and also discharges the primary cap to get ready for the next firing cycle. >> >> This is a very novel idea which I would like to >> learn more about. Has someone posted an article on >> the operational theory behind this setup? I am >> throwing out a lot of guesses and think it's time >> for me to hush until I learn more. :) Mostly just making it up as I go along and people add suggestions ;-)) Here is a text file of posts on this subject: http://hot-streamer.com/temp/Off-LineTeslaCoils(OLTC).txt Here is a web page: http://hot-streamer.com/OLTC/ You can also see older and the latest posts here if your not on the list: http://www.pupman.com/listarchives/2002/August/threads.html http://www.pupman.com/listarchives/2002/August/maillist.html All the posts start with "OLTC". You can send posts direct to me at: twftesla@qwest.net Cheers, Terry >> >> -Brian >> >> > Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Wed, 14 Aug 2002 19:00:41 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Wed, 14 Aug 2002 17:51:19 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: OLTC - Primer X-Mailing-List: archive/latest/1020 X-Loop: tesla@pupman.com Original poster: "Terry Fritz" Hi All, Since I am doing just "busy work" on the coil that is not too interesting, I thought I would put together a little primer on the whole OLTC thing. Here is the "basic" diagram of the Off-Line Tesla Coil (OLTC): http://hot-streamer.com/temp/OLTC8-14-01.gif There is really very little to it. No variacs and no high voltage transformers. Thus, it is very light weight. It plugs into your 240 VAC dryer outlet. Basically, the AC voltage is rectified by a simple beefy bridge rectifier ($4 from DigiKey) through an inductor to charge a 47uF cap. The cap is actually ten 4.7uF 600V caps that look much like the Geek group's MMC caps). Ten IGBTs act as the spark gap: http://hot-streamer.com/temp/P8050015.jpg Little heat, no sound, no light... I think it will dissipate about 30 watts. About 400 watts less then a normal gap ;-) The primary is actually a single turn at only 500nH (0.5uH). Very low inductance and very low resistance (loss): http://hot-streamer.com/temp/P8060019.jpg The secondary is a very high inductance (600mH coil) made from #28 wire. It is not made yet but will look much like the secondary in this photo (note the more complete primary too): http://hot-streamer.com/temp/P8100020.jpg The IGBT controller is an electronic circuit the monitors the current to the cap and decides when and how long to run the IGBTs. I looks like this: http://hot-streamer.com/temp/OLTC-PowerContFront.jpg http://hot-streamer.com/temp/OLTCigbtC-8-12-03.jpg Just a hand full of parts plugged into a protoboard. http://hot-streamer.com/temp/OLTCigbtC-8-13-03.gif Your done! That is all there is to the thing!! Just a rectifier, inductor, cap, primary, IGBT array, electronic controller, secondary, top load... and you have a coil! Very simple (but very "different" in theory). This is what I am trying to do. It is not built yet and the thing has never been demonstrated to actually work in any form. It's all just theory and computer models ;-)) However, it is taking shape fast ;-) Here is the bridge rectifier part with fuses and other general power control "stuff" to connect the 240VAC to the coil: http://hot-streamer.com/temp/OLTCcontFRONT.jpg http://hot-streamer.com/temp/OLTCcontSCHEM.gif http://hot-streamer.com/temp/OLTCcontTOP1.jpg http://hot-streamer.com/temp/OLTCcontTOP2.jpg The MOVs have to be about 700 volt types rather than 240 volt ones as modeling has showed. I have been spending a lot of time with computer models like: http://hot-streamer.com/temp/OLTCigbtC-8-13-01.gif But I have a lot of stuff on order and coming in so it should be taking shape fast :-)) Will be spending time on the IGBT array and inductor next. Maybe this will help bring some folk up to speed on this whole thing ;-) Cheers, Terry Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Wed, 14 Aug 2002 20:04:56 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Wed, 14 Aug 2002 19:58:32 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: Re: OLTC - Primer X-Mailing-List: archive/latest/1022 X-Loop: tesla@pupman.com Original poster: "tesla by way of Terry Fritz " Hi Terry et al Been looking at the computer model schematic. Wondered if it needed a low value for Rp to be added ?. Perhaps it would provide a sensitivity analysis of Rp to Vs. Best Ted L in NZ Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Wed, 14 Aug 2002 21:18:07 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Wed, 14 Aug 2002 21:11:40 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: Re: OLTC - Primer X-Mailing-List: archive/latest/1026 X-Loop: tesla@pupman.com Original poster: "Terry Fritz" Hi Ted, You have been looking close :-)) The switch in the schematic has the primary resistance hidden in its definitions. "Tonights" schematic has them more visible ;-)) http://hot-streamer.com/temp/OLTC8-14-02.gif If we have a 32kHz operating frequency with a 500nH primary, we can calculate the Xz impedance as only 0.1 ohm! The primary impedance must be "extremely" low for the system to oscillate. However, the IGBTs can do 2000 amps with 5 volts drop. That is 0.0025 ohm (actually better (~0.001) in a dynamic model case). The 10 caps in parallel are 0.0004 ohm at 3.8nH! So it is up to the primary to be low loss too, and it's all done and working ;-) The primary sure "looks" like an inductive dead short :-)) BTW - I have been trying to get this model so it can be downloaded, but some model redefinitions and such make it very hard to transport and have work... Many bugs in MicroSim 9.1... Grrrrr... Cheers, Terry At 01:42 PM 8/15/2002 +1200, you wrote: >Hi Terry et al > >Been looking at the computer model schematic. >Wondered if it needed a low value for Rp to be added ?. Perhaps it would >provide a sensitivity analysis of Rp to Vs. >Best >Ted L in NZ > Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Wed, 14 Aug 2002 22:13:58 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Wed, 14 Aug 2002 22:10:26 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: Re: OLTC - Primer X-Mailing-List: archive/latest/1032 X-Loop: tesla@pupman.com Original poster: "Malcolm Watts by way of Terry Fritz " Hi Terry, I'd be tempted to run a sim with a 500nH inductor and 47uF and see just how low total primary AC resistance has to go to score a Q of 10 or so (typical of a half decent SG coil) at your proposed operating frequency. Regards, malcolm On 14 Aug 2002, at 21:11, Tesla list wrote: > Original poster: "Terry Fritz" > > Hi Ted, > > You have been looking close :-)) > > The switch in the schematic has the primary resistance hidden in its > definitions. "Tonights" schematic has them more visible ;-)) > > http://hot-streamer.com/temp/OLTC8-14-02.gif > > If we have a 32kHz operating frequency with a 500nH primary, we can > calculate the Xz impedance as only 0.1 ohm! The primary impedance must be > "extremely" low for the system to oscillate. However, the IGBTs can do > 2000 amps with 5 volts drop. That is 0.0025 ohm (actually better (~0.001) > in a dynamic model case). The 10 caps in parallel are 0.0004 ohm at 3.8nH! > So it is up to the primary to be low loss too, and it's all done and > working ;-) The primary sure "looks" like an inductive dead short :-)) > > BTW - I have been trying to get this model so it can be downloaded, but > some model redefinitions and such make it very hard to transport and have > work... Many bugs in MicroSim 9.1... Grrrrr... > > Cheers, > > Terry > > > At 01:42 PM 8/15/2002 +1200, you wrote: > >Hi Terry et al > > > >Been looking at the computer model schematic. > >Wondered if it needed a low value for Rp to be added ?. Perhaps it would > >provide a sensitivity analysis of Rp to Vs. > >Best > >Ted L in NZ > > > > > Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Wed, 14 Aug 2002 23:48:02 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Wed, 14 Aug 2002 23:42:45 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: Re: OLTC - Primer X-Mailing-List: archive/latest/1034 X-Loop: tesla@pupman.com Original poster: "Terry Fritz" Hi Malcolm, At 04:01 PM 8/15/2002 +1200, you wrote: >Hi Terry, > I'd be tempted to run a sim with a 500nH inductor and 47uF >and see just how low total primary AC resistance has to go to score a >Q of 10 or so (typical of a half decent SG coil) at your proposed >operating frequency. > >Regards, >malcolm > We have a cap, IGBT array, and a primary coil. The cap specs are, for ten in Parallel (done well), 0.4 mOhms (0.0004) 3.8nH. The IGBTs have an effective resistance of about 0.001 ohms!! The primary coil is 14 inches in diameter of three parallel 1/2 inch copper tubes: http://hot-streamer.com/temp/P8140005.jpg F0 = 33kHz. So we are dealing with "really small" impedances here :-)) It seems crazy passing such low (500V) through such low impedances (milliohms) to get oscillation, but that is what this thing is about... We are looking at 3000-5000 amp peak primary currents too! Sounds "odd", but no HV tranny and no variacs... A very different machine indeed ;-)) Hehehehehe!! Cheers, Terry Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Thu, 15 Aug 2002 09:01:15 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Thu, 15 Aug 2002 08:43:26 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: Re: OLTC - Primer X-Mailing-List: archive/latest/1036 X-Loop: tesla@pupman.com Original poster: "Marco Denicolai by way of Terry Fritz " Terry, just a simple suggestion for your OLTC prototype. Remember to mount/engineer the IGBT string so that the substitution of a damaged device is not a pain in the *** but just a fast welder exercise. I'm afraid you'll have to replace some of those IGBTs, and having to take apart all the string to change one or two devices will make the operation more tedious. Use a good glass-fiber PCB, or your pads will be scratched away after 1-2 IGBT replacements. I'm following this project with interest. Keep us informed. Best Regards Tesla list wrote: > > Original poster: "Terry Fritz" > So we are dealing with "really small" impedances here :-)) It seems crazy > passing such low (500V) through such low impedances (milliohms) to get > oscillation, but that is what this thing is about... We are looking at > 3000-5000 amp peak primary currents too! ============================================================ The information contained in this message may be privileged and confidential and protected from disclosure. If the reader of this message is not the intended recipient, or an employee or agent responsible for delivering this message to the intended recipient, you are hereby notified that any reproduction, dissemination or distribution of this communication is strictly prohibited. If you have received this communication in error, please notify us immediately by replying to the message and deleting it from your computer. Thank you. Tellabs ============================================================ Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Thu, 15 Aug 2002 12:45:45 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Thu, 15 Aug 2002 12:41:05 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: Re: OLTC - Primer X-Mailing-List: archive/latest/1047 X-Loop: tesla@pupman.com Original poster: "Terry Fritz" Hi Marco, At 10:12 AM 8/15/2002 +0300, you wrote: >Terry, > >just a simple suggestion for your OLTC prototype. Remember to >mount/engineer the IGBT string so that the substitution of a damaged >device is not a pain in the *** but just a fast welder exercise. I'm >afraid you'll have to replace some of those IGBTs, and having to take >apart all the string to change one or two devices will make the >operation more tedious. Use a good glass-fiber PCB, or your pads will be >scratched away after 1-2 IGBT replacements. > >I'm following this project with interest. Keep us informed. > >Best Regards > I am not too worried about voltage, but right now the current is probably too high for the IGBTs at full power. I am leaving it as is and will change things once I have some real testing done. The IGBTs are mounted directly to copper conductors (no PC boards) so they are easy to replace. I went to K-10 Sil pads to isolate the collectors from the heatsink and to get ride of that nasty thermal grease. I suspect I will have to redesign the IGBT mounting and all later, but what I have now will work for testing and to collect data for the next revision. The thing is on 5 amps fuses, I am thinking the IGBTs will often win if something does not go right. Another advantage of having the IGBTs on independent caps is that a failure will be fairly well isolated and easy to find. Having the IGBTs in parallel would have made finding a bad one hard (of course, they would probably all be bad in that case). I am trying to get enough silicon in the IGBTs so that they can absorb the full energy of the coil (until the fuses blow) if something goes bad. If I redo it, I will go to isolated heatsinks so I don't have the sil pads. They add thermal resistance which could be critical if the IGBTs become the "load". I want the coil to be able to survive some pretty nasty fault conditions. Replacing parts whenever something goes bad will "hopefully" be avoided. I want it to be super tough since Tesla coils have a habit of things going bad, especially when others try to reproduce it :-)) If the IGBTs stay open, there is no problem. If they stay closed, they can easily survive the AC fault current till the fuses explode. They are pretty hard wired in parallel operation so they should 'all' be either on or off without any "only three IGBTs on" situations...) Right now current is a concern, but that is just a matter of adding more IGBTs. There is a situation were the coil could be running without a secondary and all the power goes... Somewhere... I would like the IGBTs to take that power for a length of time if needed. They really should not fail easily. The only thing I am really not considering right now are direct streamer hits to the array. However, if a streamer hits it, the whole project is a success :-)) The big danger to the IGBTs will be latter if the thing works and "everybody" starts making OLTCs. The real test of how tough it is will be to see if it is so tough the anyone can cobble an OLTC together and have it work well ;-)) It certainly is simple enough, but the thing has to be designed so it is very hard to damage the parts no matter what "mistakes are made" :o)) I think I will be able to do lower energy testing this weekend. That will determine the losses and give me a good idea of the actual currents and Fo frequency. I went dumpster diving this morning and got a whole lot of cores for the inductors. More parts are coming tomorrow... Cheers, Terry Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Thu, 15 Aug 2002 15:51:19 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Thu, 15 Aug 2002 15:40:30 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: Re: OLTC - Primer X-Mailing-List: archive/latest/1053 X-Loop: tesla@pupman.com Original poster: "Malcolm Watts by way of Terry Fritz " Hi Terry, On 14 Aug 2002, at 23:42, Tesla list wrote: > Original poster: "Terry Fritz" > > Hi Malcolm, > > At 04:01 PM 8/15/2002 +1200, you wrote: > >Hi Terry, > > I'd be tempted to run a sim with a 500nH inductor and 47uF > >and see just how low total primary AC resistance has to go to score a > >Q of 10 or so (typical of a half decent SG coil) at your proposed > >operating frequency. > > > >Regards, > >malcolm > > > > We have a cap, IGBT array, and a primary coil. > > The cap specs are, for ten in Parallel (done well), 0.4 mOhms (0.0004) > 3.8nH. The IGBTs have an effective resistance of about 0.001 ohms!! > > The primary coil is 14 inches in diameter of three parallel 1/2 inch copper > tubes: > > http://hot-streamer.com/temp/P8140005.jpg > > F0 = 33kHz. > > So we are dealing with "really small" impedances here :-)) It seems crazy > passing such low (500V) through such low impedances (milliohms) to get > oscillation, but that is what this thing is about... We are looking at > 3000-5000 amp peak primary currents too! > > Sounds "odd", but no HV tranny and no variacs... A very different machine > indeed ;-)) > > Hehehehehe!! > > Cheers, > > Terry It sounds pretty good on paper for sure. Regards, malcolm Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Fri, 16 Aug 2002 08:17:45 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Fri, 16 Aug 2002 08:03:56 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: Re: OLTC - Primer X-Mailing-List: archive/latest/1089 X-Loop: tesla@pupman.com Original poster: "Marco Denicolai by way of Terry Fritz " Hi Terry, Tesla list wrote: > The thing is on 5 amps fuses, I am thinking the IGBTs will often win if > something does not go right. Yeah... Sadly it really is true that the fastest fuse is the semiconductor you are trying to protect itself :) A 5A fuse that blows within 1 ms (and only when 50A or more is passed through it) is a FF rated one, that is a very fast one. The short-circuit rated IGBTs usually will last for some tenths of microseconds when short-circuited. More, you need a fuse rated for, say, 600 VDC, not just the usual ones. Otherwise the fuse will open but the current will spark over it (internally) and keep on flowing for even a longer time. You just need a thick-film resistor and a inexpensive 2N2222 or similar to protect each IGBT from overcurrent and leave time to the fuse to blow. This for the OLTC final version, I mean. >Another advantage of having the IGBTs on > independent caps is that a failure will be fairly well isolated and easy to > find. Having the IGBTs in parallel would have made finding a bad one hard > (of course, they would probably all be bad in that case). I must confess I had a 10-days vacation and I didn't dare to read through the >600 list posts (just damped them, :( ). Would you mind to explain once more this independent cap/IGBT connection scheme? >I am trying to > get enough silicon in the IGBTs so that they can absorb the full energy of > the coil (until the fuses blow) if something goes bad. In all my IGBT damages (uncountables...) the mechanism is always been the same: 1. the Vge rating (+/- 20V) is exceeded -> the gate insulation goes breakdown 2. the IGBT goes into short circuit with <1 ohm impedance between G, C and E 3. the short circuit generated blows what is capable of: another IGBT, the PCB traces, the FF (yes FF!) fuse, etc. I suggest you to tune the gate drive circuitry from the very beginning. A high collector current is usually not one of the first problems. If you have a lousy gate drive, collector current variations (e.g. transients) will be reflected onto the gate, that will amplify them back to the collector, that will (again) be seen on the gate. A kind of nice loop, thanks to the Cge and Cgc capacitances internal to each IGBT. You could start with a very slow turn on (i.e. a 100 ohm gate res) and a rock solid, low impedance turn off (just a schottky in antiparallel with the 100 ohm). Easier to deal with losses with more cooling than to replace broken devices. >If I redo it, I > will go to isolated heatsinks so I don't have the sil pads. I use a long sil "slice" cut by myslef from a larger foil. While you are replacing one IGBT, the others will keep the sil in place for you. Best Regards -- _____________________________________________________________ Marco Denicolai Senior Design Engineer Tellabs Oy tel: +358 9 4131 2769 DSL Products mobile: +358 50 353 9468 Sinikalliontie 7 fax: +358 9 4131 2410 02630 Espoo FINLAND email: marco.denicolai@tellabs.com _____________________________________________________________ ============================================================ Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Sat, 24 Aug 2002 00:06:01 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Sat, 24 Aug 2002 00:02:14 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: OLTC - Ready :-)) X-Mailing-List: archive/latest/1469 X-Loop: tesla@pupman.com Original poster: "Terry Fritz" Hi All, Tonight I wound the secondary: http://hot-streamer.com/temp/OLTC08-23-03.jpg 46 inches of #28 wire... Fortunately, the winding jig worked perfectly ;-)) Took about three hours total, but mostly fiddling. Rather than coat it with polyurethane, I wrapped it with that shipping stretch wrap stuff. Seems to work great and will protect the wire. http://hot-streamer.com/temp/OLTC08-23-04.jpg So here is the entire coil: http://hot-streamer.com/temp/OLTC08-23-05.jpg It all weighs 37 pounds total. Tuning seems pretty close right now but I will have to test all that more tomorrow. So all the hardware is there and it's ready to start testing :-))) Cheers, Terry Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Sat, 24 Aug 2002 11:18:32 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Sat, 24 Aug 2002 11:10:55 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: Re: OLTC - Ready :-)) X-Mailing-List: archive/latest/1472 X-Loop: tesla@pupman.com Original poster: "Gregory Peters by way of Terry Fritz " Terry, How can you wait another day?!? It's so close!!! Good Luck!! Greg. Quoting Tesla list : > Original poster: "Terry Fritz" > > Hi All, > > Tonight I wound the secondary: > > http://hot-streamer.com/temp/OLTC08-23-03.jpg > > 46 inches of #28 wire... Fortunately, the winding jig worked > perfectly > ;-)) Took about three hours total, but mostly fiddling. > > Rather than coat it with polyurethane, I wrapped it with that > shipping > stretch wrap stuff. Seems to work great and will protect the > wire. > > http://hot-streamer.com/temp/OLTC08-23-04.jpg > > So here is the entire coil: > > http://hot-streamer.com/temp/OLTC08-23-05.jpg > > It all weighs 37 pounds total. Tuning seems pretty close > right now but I > will have to test all that more tomorrow. > > So all the hardware is there and it's ready to start testing > :-))) > > Cheers, > > Terry > > > Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Mon, 26 Aug 2002 08:12:50 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Mon, 26 Aug 2002 08:06:28 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: Re: OLTC - Ready :-)) X-Mailing-List: archive/latest/1548 X-Loop: tesla@pupman.com Original poster: "robert heidlebaugh by way of Terry Fritz " Terry: Keep us posted on how well your shrink-wrap coating works. I've never considered a wrap coat of any kind, as you are not providing any between winding coating as added insulation. Robert H > From: "Tesla list" > Date: Sat, 24 Aug 2002 00:02:14 -0600 > To: tesla@pupman.com > Subject: OLTC - Ready :-)) > Resent-From: tesla@pupman.com > Resent-Date: Sat, 24 Aug 2002 00:04:12 -0600 > > Original poster: "Terry Fritz" > > Hi All, > > Tonight I wound the secondary: > > http://hot-streamer.com/temp/OLTC08-23-03.jpg > > 46 inches of #28 wire... Fortunately, the winding jig worked perfectly > ;-)) Took about three hours total, but mostly fiddling. > > Rather than coat it with polyurethane, I wrapped it with that shipping > stretch wrap stuff. Seems to work great and will protect the wire. > > http://hot-streamer.com/temp/OLTC08-23-04.jpg > > So here is the entire coil: > > http://hot-streamer.com/temp/OLTC08-23-05.jpg > > It all weighs 37 pounds total. Tuning seems pretty close right now but I > will have to test all that more tomorrow. > > So all the hardware is there and it's ready to start testing :-))) > > Cheers, > > Terry > > Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Mon, 26 Aug 2002 19:40:19 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Mon, 26 Aug 2002 19:38:07 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: Re: OLTC - Ready :-)) X-Mailing-List: archive/latest/1587 X-Loop: tesla@pupman.com Original poster: "Terry Fritz" Hi Robert, The shrink wrap seems to work great! I looked at it tonight and the burns holes were very clean. It seems to protect the coil very well (that plastic stuff is VERY resiliant!!) It is available in almost any office supply place and probably hardware places too. One thing I like is it is fast and clean. No messy smelly poly coating or anything. If you put in on the same time you wind the coil on a winder it is just too easy. It certainly does not provide much added insulation between windings (I am not sure polly helps either there). But I really like it so far!! Cheers, Terry At 07:32 AM 8/26/2002 -0600, you wrote: >Terry: Keep us posted on how well your shrink-wrap coating works. I've never >considered a wrap coat of any kind, as you are not providing any between >winding coating as added insulation. > Robert H > > Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Wed, 28 Aug 2002 12:01:15 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Wed, 28 Aug 2002 11:48:45 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: Re: OLTC - Ready :-)) X-Mailing-List: archive/latest/1665 X-Loop: tesla@pupman.com Original poster: "by way of Terry Fritz " In a message dated 8/26/02 6:39:53 PM Pacific Daylight Time, tesla@pupman.com writes: > > Hi Robert, > > The shrink wrap seems to work great! I looked at it tonight and the burns > holes were very clean. It seems to protect the coil very well (that > plastic stuff is VERY resiliant!!) It is available in almost any office > supply place and probably hardware places too. One thing I like is it is > fast and clean. No messy smelly poly coating or anything. If you put in > on the same time you wind the coil on a winder it is just too easy. > > It certainly does not provide much added insulation between windings (I am > not sure polly helps either there). But I really like it so far!! > > Cheers, > > Terry Terry, I used a whole roll of glad wrap on one of my secondaries. I believe it is polyethylene. Most are not. Ed Sonderman Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Wed, 21 Aug 2002 22:48:31 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Wed, 21 Aug 2002 22:45:06 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: OLTC - Silly trick X-Mailing-List: archive/latest/1384 X-Loop: tesla@pupman.com Original poster: "Terry Fritz" Hi All, I stuck the secondary and toroid from my big coil on the OLTC. Probably pretty close to what the real one would look like: http://hot-streamer.com/temp/OLTC08-21-06.jpg Of course, it is not even close to tuning with this coil or anything, but I turned it on anyway at very low power: http://hot-streamer.com/temp/OLTC08-21-07.jpg Only about a 3/16" spark, but enough to light a bulb relly nice :o)) Cheers, Terry Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Fri, 16 Aug 2002 17:34:19 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Fri, 16 Aug 2002 17:22:56 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: OLTC - Split core inductors X-Mailing-List: archive/latest/1123 X-Loop: tesla@pupman.com Original poster: "Terry Fritz" Hi All, I have been learning a whole lot more about inductors than I ever wanted to know :-p A closed iron inductor that can take about 5 amps, 120Hz, 150mH, and 3 ohms DC resistance would be very large due to saturation (also has those odd non-linearities). The inductor should not be over 3 ohms of DC resistance since it hurts the resonant charging (5 amps at 3 ohms is also 75 watts!): http://hot-streamer.com/temp/OLTC08-16-05.gif So I looked at air core inductors using the information at this nice site: http://www.ee.surrey.ac.uk/Workshop/advice/coils/air_coils.html I did a lot of math and Excel stuff and came up with this list of "possibilities": http://hot-streamer.com/temp/OLTC08-16-06.gif It is based off the needed inductance, resistance, and wire data. There are no practical solutions!! For example a #12 wire coil 13.5 inches in diameter with 2300 feet of wire at 60 pounds!! The spreadsheet is here if anyone cares: http://hot-streamer.com/temp/airwire%20chart.xls So we are looking at a big split core inductor like my split variac core: http://hot-streamer.com/temp/OLTC8150009.jpg It measures 47mH so I need SQRT(150/47) = 1.79 as many turns on it. Very possible... It is only 0.4 ohms DC resistance right now and it has excellent V/I and inductor characteristics. I am sure a MOT core or any big iron core be used too. Sad, we need iron, but the H*** with it ;-)) It really only weighs 3 pounds 14 onces... More research later will be need into these inductors and figuring out how to make them easy for anyone to reproduce. Now I know why my request for ideas on inductors went unanswered ;-)) I ain't easy... I also got the caps today from Richardson electronics. Took three weeks and I didn't know if they were ever really going to come, but they did. Chris was also getting caps for me :-| No worries, I think we can find a use for them in the higher power version :-)) Much construction work to do... Cheers, Terry Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Fri, 16 Aug 2002 21:00:00 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Fri, 16 Aug 2002 20:53:00 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: OLTC - Split core inductors X-Mailing-List: archive/latest/1140 X-Loop: tesla@pupman.com Original poster: "Terry Fritz" Hi All, I wrapped more turns around my old variac core that I slit with a cobalt hacksaw. http://hot-streamer.com/temp/OLTC08-16-08.jpg http://hot-streamer.com/temp/OLTC8150009.jpg It's impedance should be: Rl = 2 x pi x 60 x L = 56.6 ohms So with 90 volts input, I should get 1.59 amps: http://hot-streamer.com/temp/OLTC08-16-09.gif Pretty close ;-)) It goes into saturation at about 2 amps still: http://hot-streamer.com/temp/OLTC08-16-10.gif At 120 Hz,instead of 60, that should double to about 4 amps. I need 5 amps: http://hot-streamer.com/temp/OLTC08-16-07.gif Interesting to note that if one were to bias the core with -2.5 amps DC, you could probably cut the amount of iron in the core by 1/2! But the extra iron is probably simpler... So it is just barely there, good enough for now ;-)) Richard wrote: "Replace them with much smaller LC tank circuits tuned to the frequency you wish to pass. Tank R can be held really low and at resonance Z can be made zero. If you play a little with Fo you can get some really interesting band pass filters. You can make these little LC filters tunable and put in as much tank Z as you desire. Disassemble a flyback core and wind your much smaller inductor. Don't forget to put the shims back in." A wild idea I need to look into :-))) Cheers, Terry Cheers, Terry Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Fri, 16 Aug 2002 23:22:05 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Fri, 16 Aug 2002 23:10:35 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: Re: OLTC - Split core inductors X-Mailing-List: archive/latest/1150 X-Loop: tesla@pupman.com Original poster: "Jim Lux by way of Terry Fritz " Look at those tape wound air core inductors, remarkably high inductance in a fairly inexpensive small package.. and, I'll bet that a simple core might jack the inductance up pretty high. ----- Original Message ----- From: "Tesla list" To: Sent: Friday, August 16, 2002 4:22 PM Subject: OLTC - Split core inductors > Original poster: "Terry Fritz" > > Hi All, > > I have been learning a whole lot more about inductors than I ever wanted to > know :-p > > A closed iron inductor that can take about 5 amps, 120Hz, 150mH, and 3 ohms > DC resistance would be very large due to saturation (also has those odd > non-linearities). The inductor should not be over 3 ohms of DC resistance > since it hurts the resonant charging (5 amps at 3 ohms is also 75 watts!): > > http://hot-streamer.com/temp/OLTC08-16-05.gif > > So I looked at air core inductors using the information at this nice site: > > http://www.ee.surrey.ac.uk/Workshop/advice/coils/air_coils.html > > I did a lot of math and Excel stuff and came up with this list of > "possibilities": > > http://hot-streamer.com/temp/OLTC08-16-06.gif > > It is based off the needed inductance, resistance, and wire data. > > There are no practical solutions!! For example a #12 wire coil 13.5 inches > in diameter with 2300 feet of wire at 60 pounds!! > > The spreadsheet is here if anyone cares: > > http://hot-streamer.com/temp/airwire%20chart.xls > > So we are looking at a big split core inductor like my split variac core: > > http://hot-streamer.com/temp/OLTC8150009.jpg > > It measures 47mH so I need SQRT(150/47) = 1.79 as many turns on it. Very > possible... It is only 0.4 ohms DC resistance right now and it has > excellent V/I and inductor characteristics. I am sure a MOT core or any > big iron core be used too. Sad, we need iron, but the H*** with it ;-)) > It really only weighs 3 pounds 14 onces... More research later will be > need into these inductors and figuring out how to make them easy for anyone > to reproduce. Now I know why my request for ideas on inductors went > unanswered ;-)) I ain't easy... > > I also got the caps today from Richardson electronics. Took three weeks > and I didn't know if they were ever really going to come, but they did. > Chris was also getting caps for me :-| No worries, I think we can find a > use for them in the higher power version :-)) > > Much construction work to do... > > Cheers, > > Terry > > > > > > > Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Sat, 17 Aug 2002 10:55:49 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Sat, 17 Aug 2002 10:43:46 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: Re: OLTC - Split core inductors X-Mailing-List: archive/latest/1160 X-Loop: tesla@pupman.com Original poster: "Eddie Burwell by way of Terry Fritz " In this application the resonant charging inductor is only going to pass current in one direction. The field is going to swing from zero to +saturation(or near it). If the core could be biased to -saturation and swing to +saturation it could be half the physical size. This could be done with either a bias winding or permant magnets. Permant magnets probably won't get the core all the way to -saturation, however, they are simple. Ferrite magnets are nice because they have high resistivity, though their strength is not so good. NdFeB magnets have lower resistivity and might heat up a bit, but they would provide a nice bias field. Food for thought. Eddie Burwell Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Sat, 17 Aug 2002 12:36:12 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Sat, 17 Aug 2002 12:26:52 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: Re: OLTC - Split core inductors X-Mailing-List: archive/latest/1169 X-Loop: tesla@pupman.com Original poster: "Ed Phillips by way of Terry Fritz " Tesla list wrote: > > Original poster: "Jim Lux by way of Terry Fritz " > > Look at those tape wound air core inductors, remarkably high inductance in a > fairly inexpensive small package.. and, I'll bet that a simple core might > jack the inductance up pretty high. No way! Those cores will saturate very easily, and in fact are designed to do so. Furthermore, their inductance will vary with excitation voltage. You still need enough core area and turns/volt!!!!!!!!!!!!!!! Ed Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Sat, 17 Aug 2002 12:55:57 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Sat, 17 Aug 2002 12:51:18 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: Re: OLTC - Split core inductors X-Mailing-List: archive/latest/1175 X-Loop: tesla@pupman.com Original poster: "Terry Fritz" Hi Ed and Jim, I think Jim was referring to inductors made of wide copper ribbon but with no metal core, just air. If anyone has a link or info on these, I can check into this. I may be a solution if the copper/kapton does not get too expensive. Simple to make and low resistance for sure! They use these at work for some things but I know little about the theory or design equations behind them. The spec would be: 150mH 5 amps peak ~1 ohm or less of resistance. The copper could probably be very thin. DigiKey sells 0.75 inch kapton but other tapes would work too in this less than human space flight application ;-) MSC has two inch wide, 0.005 inch copper ribbon for $52/100 feet. 2-inch platting tape could be used I bet (tough, thin and cheaper than kapton). Just have to know the equation to use. I quickly searched Google but didn't find much. Even paper or poly would work... Cheers, Terry At 10:45 AM 8/17/2002 -0700, you wrote: >Tesla list wrote: >> >> Original poster: "Jim Lux by way of Terry Fritz " > >> >> Look at those tape wound air core inductors, remarkably high inductance in a >> fairly inexpensive small package.. and, I'll bet that a simple core might >> jack the inductance up pretty high. > > No way! Those cores will saturate very easily, and in fact are >designed to do so. Furthermore, their inductance will vary with >excitation voltage. You still need enough core area and >turns/volt!!!!!!!!!!!!!!! > >Ed > Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Sat, 17 Aug 2002 17:16:30 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Sat, 17 Aug 2002 16:39:04 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: Re: OLTC - Split core inductors X-Mailing-List: archive/latest/1182 X-Loop: tesla@pupman.com Original poster: "Ed Phillips by way of Terry Fritz " Tesla list wrote: > > Original poster: "Terry Fritz" > > Hi Ed and Jim, > > I think Jim was referring to inductors made of wide copper ribbon but with > no metal core, just air. If anyone has a link or info on these, I can > check into this. I may be a solution if the copper/kapton does not get too > expensive. Simple to make and low resistance for sure! They use these at > work for some things but I know little about the theory or design equations > behind them. The spec would be: > > 150mH > 5 amps peak > ~1 ohm or less of resistance. > > The copper could probably be very thin. DigiKey sells 0.75 inch kapton but > other tapes would work too in this less than human space flight application ;-) > > MSC has two inch wide, 0.005 inch copper ribbon for $52/100 feet. 2-inch > platting tape could be used I bet (tough, thin and cheaper than kapton). Maybe you're right! I overlooked the "air"! But, if so, I've never heard of them and would also be curious. For the record, many high-power traveling-wave amplifiers use a focussing solenoid wound with aluminum foil and insulated only with the oxide film on the aluminum. At least that's what I was told by an engineer at the old Hughes Electron Devices Division. I have no idea as to how to calculate the inductance, but perhaps Paul or someone else on the list can work it out. Ed Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Sat, 17 Aug 2002 17:13:31 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Sat, 17 Aug 2002 16:53:56 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: Re: OLTC - Split core inductors X-Mailing-List: archive/latest/1192 X-Loop: tesla@pupman.com Original poster: "Jim Lux by way of Terry Fritz " Good point... no way are you going to get enough core area.. ----- Original Message ----- From: "Tesla list" To: Sent: Saturday, August 17, 2002 11:26 AM Subject: Re: OLTC - Split core inductors > Original poster: "Ed Phillips by way of Terry Fritz " > > Tesla list wrote: > > > > Original poster: "Jim Lux by way of Terry Fritz " > > > > > Look at those tape wound air core inductors, remarkably high inductance in a > > fairly inexpensive small package.. and, I'll bet that a simple core might > > jack the inductance up pretty high. > > No way! Those cores will saturate very easily, and in fact are > designed to do so. Furthermore, their inductance will vary with > excitation voltage. You still need enough core area and > turns/volt!!!!!!!!!!!!!!! > > Ed > > > Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Sat, 17 Aug 2002 17:13:31 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Sat, 17 Aug 2002 16:56:28 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: Re: OLTC - Split core inductors X-Mailing-List: archive/latest/1191 X-Loop: tesla@pupman.com Original poster: "Jim Lux by way of Terry Fritz " The link was in a post in the archives ().. http:/www.alphacore.com/inductor.hm > Original poster: "Terry Fritz" > > Hi Ed and Jim, > > I think Jim was referring to inductors made of wide copper ribbon but with > no metal core, just air. If anyone has a link or info on these, I can > check into this. I may be a solution if the copper/kapton does not get too > expensive. Simple to make and low resistance for sure! They use these at > work for some things but I know little about the theory or design equations > behind them. The spec would be: > > 150mH > 5 amps peak > ~1 ohm or less of resistance. > > The copper could probably be very thin. DigiKey sells 0.75 inch kapton but > other tapes would work too in this less than human space flight application ;-) > > MSC has two inch wide, 0.005 inch copper ribbon for $52/100 feet. 2-inch > platting tape could be used I bet (tough, thin and cheaper than kapton). > Just have to know the equation to use. I quickly searched Google but > didn't find much. Even paper or poly would work... > > Cheers, > > Terry > > At 10:45 AM 8/17/2002 -0700, you wrote: > >Tesla list wrote: > >> > >> Original poster: "Jim Lux by way of Terry Fritz " > > > >> > >> Look at those tape wound air core inductors, remarkably high inductance in a > >> fairly inexpensive small package.. and, I'll bet that a simple core might > >> jack the inductance up pretty high. > > > > No way! Those cores will saturate very easily, and in fact are > >designed to do so. Furthermore, their inductance will vary with > >excitation voltage. You still need enough core area and > >turns/volt!!!!!!!!!!!!!!! > > > >Ed > > > > Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Sat, 17 Aug 2002 17:25:05 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Sat, 17 Aug 2002 17:20:34 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: Re: OLTC - Split core inductors X-Mailing-List: archive/latest/1194 X-Loop: tesla@pupman.com Original poster: "Terry Fritz" At 03:00 PM 8/17/2002 -0700, you wrote: >The link was in a post in the archives ().. > Hi Jim, http://www.alphacore.com/inductor.htm Wow! They have all the cool stuff we need. I recognize most if it since it is used at work. From the charts, it sounds like they "could" make the air inductor but it would be large and expensive. However, check out these cores! http://www.alphacore.com/stcores.htm A big 1200 watt one is only $21. Just a saw cut away from being just like my variac core. Online ordering too!! Looks like a great place to get this stuff from!!! Cheers, Terry Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Sun, 18 Aug 2002 11:52:28 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Sun, 18 Aug 2002 11:42:20 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: Re: OLTC - Split core inductors X-Mailing-List: archive/latest/1229 X-Loop: tesla@pupman.com Original poster: "Bert Pool by way of Terry Fritz " Terry, You might want to look at using a "metglass" core. This stuff makes for incredible inductor cores, and is much more readily available than just a few years ago. This might allow the design of a more reasonable size inductor with the saturation characteristics you need. Bert Pool At 05:22 PM 8/16/02 -0600, you wrote: >Original poster: "Terry Fritz" > >Hi All, > >I have been learning a whole lot more about inductors than I ever wanted to >know :-p > >A closed iron inductor that can take about 5 amps, 120Hz, 150mH, and 3 ohms >DC resistance would be very large due to saturation (also has those odd >non-linearities). The inductor should not be over 3 ohms of DC resistance >since it hurts the resonant charging (5 amps at 3 ohms is also 75 watts!): > >http://hot-streamer.com/temp/OLTC08-16-05.gif > >So I looked at air core inductors using the information at this nice site: > >http://www.ee.surrey.ac.uk/Workshop/advice/coils/air_coils.html > >I did a lot of math and Excel stuff and came up with this list of >"possibilities": > >http://hot-streamer.com/temp/OLTC08-16-06.gif > >It is based off the needed inductance, resistance, and wire data. > >There are no practical solutions!! For example a #12 wire coil 13.5 inches >in diameter with 2300 feet of wire at 60 pounds!! > >The spreadsheet is here if anyone cares: > >http://hot-streamer.com/temp/airwire%20chart.xls > >So we are looking at a big split core inductor like my split variac core: > >http://hot-streamer.com/temp/OLTC8150009.jpg > >It measures 47mH so I need SQRT(150/47) = 1.79 as many turns on it. Very >possible... It is only 0.4 ohms DC resistance right now and it has >excellent V/I and inductor characteristics. I am sure a MOT core or any >big iron core be used too. Sad, we need iron, but the H*** with it ;-)) >It really only weighs 3 pounds 14 onces... More research later will be >need into these inductors and figuring out how to make them easy for anyone >to reproduce. Now I know why my request for ideas on inductors went >unanswered ;-)) I ain't easy... > >I also got the caps today from Richardson electronics. Took three weeks >and I didn't know if they were ever really going to come, but they did. >Chris was also getting caps for me :-| No worries, I think we can find a >use for them in the higher power version :-)) > >Much construction work to do... > >Cheers, > > Terry > > > > > Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Sun, 18 Aug 2002 16:12:31 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Sun, 18 Aug 2002 16:04:17 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: Re: OLTC - Split core inductors X-Mailing-List: archive/latest/1258 X-Loop: tesla@pupman.com Original poster: "Ed Phillips by way of Terry Fritz " Tesla list wrote: > > Original poster: "Bert Pool by way of Terry Fritz " > > Terry, > You might want to look at using a "metglass" core. This stuff makes for > incredible inductor cores, and is much more readily available than just a > few years ago. This might allow the design of a more reasonable size > inductor with the saturation characteristics you need. > Bert Pool I'm not sure how much better those new cores would really be for Terry's purposes. They do have a lot less "iron loss" but don't necessarily work at higher flux densities. Ed Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Mon, 26 Aug 2002 21:58:45 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Mon, 26 Aug 2002 21:56:28 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: OLTC - The Arrival :-)) X-Mailing-List: archive/latest/1599 X-Loop: tesla@pupman.com Original poster: "B2 by way of Terry Fritz " Hi Terry: Congratulations on your wonderful, and elegant, design! Thank you for sharing the juicy details! Cheers, Barry Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Tue, 3 Sep 2002 21:45:20 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Tue, 03 Sep 2002 21:41:41 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: OLTC idea... X-Mailing-List: archive/latest/2032 X-Loop: tesla@pupman.com Original poster: "Wells Campbell by way of Terry Fritz " Hi Terry, all, I am writing with a kind of an oddball idea which I had a few years ago, and actually made it work on my little desktop coil, and had forgotten it completely until today as I was daydreaming...maybe it's a concept that would have some use in the OLTC realm, who knows... Let me first take you back to the heyday of rolled poly caps and Richard Quick gaps, about the time when the first little blue boxy-looking phillips caps were being soldered together and all the "high power guys" were scoffing at the idea of an MMC being used for anything but a little coil...A post about rolled poly caps talked about reducing inductance in the rolled caps by using strips of foil every turn or two as a terminal, so that the charge didn't have to travel around and around the plate to get to the terminal. well, I got to thinking, what if you could make a cap that had about the inducance of a primary, wrapped around a tube which would go around the secondary and serve as both the primary and cap in one unit-I think I called it a capductor or incapacitator or something, and got some copper foil and twisted one up. The way it worked was that each plate had it's terminal at opposing ends, so that the charge had to travel in the direction that contributed to the magnetic field instead of cancelling it out. I wrapped the plate/poly/plate/poly stack around a tube which fit around my secondary with about an inch of clearance, and was about 1/3 as high as my secondary, with about 8 turns total. The gap and supply went in parallel to the "incapacitator", and it resonated with itself. (I know, hurts to think about, but basically the inductive properties and the capacitive properties produced a unit that resonated at the same frequency as my secondary, and served as a primary and cap in one). It actually worked! I got the values so close on the first try that I was able to tune with 3/4 turn of refrig. tubing, off axis. Anyway, my reasoning was that it would be the lowest loss arrangement ever, because the energy wouldn't have to travel out of the capacitor, into the primary, and back, but would just be rocking back and forth along the plates of the incapacitator. I dunno, maybe you could construct a poly and copper plate cap that would wrap around the base of the OLTC, and simply connect the IGBT "brick" across the leads of the incapacitator? you would have to get the values right in designing the thing, but that shouldn't be too hard, I did it with wintesla. Anyway, just an idea, I thought it was a neat concept at the time, but never got much farther than cobble-up. But it was neat seeing "noodle theory" turn into reality :>). Does this sound like anything you could use? -- Wells Campbell wellscampbell@onebox.com Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Tue, 3 Sep 2002 23:08:35 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Tue, 03 Sep 2002 21:49:27 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: Re: OLTC idea... X-Mailing-List: archive/latest/2039 X-Loop: tesla@pupman.com Original poster: "Terry Fritz" Hi Wells, I was originally thinking of having the primary caps as part of the inductive loop. As it "turned out", the caps were brought outside the loop. I was afraid that the cap being "part" of the 4500Amp primary may do something unforseen. I don't "know" of anything bad, but I didn't want to take a chance and the thing sort of worked out to what it is now. I think Ken's coil may use this for his single loop primary? Cheers, Terry At 08:30 PM 9/3/2002 -0700, you wrote: >Hi Terry, all, > >I am writing with a kind of an oddball idea which I had a few years ago, >and actually made it work on my little desktop coil, and had forgotten >it completely until today as I was daydreaming...maybe it's a concept >that would have some use in the OLTC realm, who knows... > >Let me first take you back to the heyday of rolled poly caps and Richard >Quick gaps, about the time when the first little blue boxy-looking phillips >caps were being soldered together and all the "high power guys" were >scoffing at the idea of an MMC being used for anything but a little coil...A >post about rolled poly caps talked about reducing inductance in the rolled >caps by using strips of foil every turn or two as a terminal, so that >the charge didn't have to travel around and around the plate to get to >the terminal. > >well, I got to thinking, what if you could make a cap that had about >the inducance of a primary, wrapped around a tube which would go around >the secondary and serve as both the primary and cap in one unit-I think >I called it a capductor or incapacitator or something, and got some copper >foil and twisted one up. The way it worked was that each plate had it's >terminal at opposing ends, so that the charge had to travel in the direction >that contributed to the magnetic field instead of cancelling it out. >I wrapped the plate/poly/plate/poly stack around a tube which fit around >my secondary with about an inch of clearance, and was about 1/3 as high >as my secondary, with about 8 turns total. The gap and supply went in >parallel to the "incapacitator", and it resonated with itself. (I know, >hurts to think about, but basically the inductive properties and the >capacitive properties produced a unit that resonated at the same frequency >as my secondary, and served as a primary and cap in one). It actually >worked! I got the values so close on the first try that I was able to >tune with 3/4 turn of refrig. tubing, off axis. > >Anyway, my reasoning was that it would be the lowest loss arrangement >ever, because the energy wouldn't have to travel out of the capacitor, >into the primary, and back, but would just be rocking back and forth >along the plates of the incapacitator. > >I dunno, maybe you could construct a poly and copper plate cap that would >wrap around the base of the OLTC, and simply connect the IGBT "brick" >across the leads of the incapacitator? you would have to get the values >right in designing the thing, but that shouldn't be too hard, I did it >with wintesla. > >Anyway, just an idea, I thought it was a neat concept at the time, but >never got much farther than cobble-up. But it was neat seeing "noodle >theory" turn into reality :>). > >Does this sound like anything you could use? > >-- >Wells Campbell >wellscampbell@onebox.com > > > Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Wed, 4 Sep 2002 08:32:28 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Wed, 04 Sep 2002 08:23:38 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: Re: OLTC idea... X-Mailing-List: archive/latest/2040 X-Loop: tesla@pupman.com Original poster: "Wells Campbell by way of Terry Fritz " ---- "Tesla list" wrote: > Original poster: "Terry Fritz" > > Hi Wells, > > I was originally thinking of having the primary caps as part of the > inductive loop. As it "turned out", the caps were brought outside > the > loop. I was afraid that the cap being "part" of the 4500Amp primary > may do > something unforseen. I don't "know" of anything bad, but I didn't > want to > take a chance and the thing sort of worked out to what it is now. > I think > Ken's coil may use this for his single loop primary? > > Cheers, > > Terry > > Terry, Yeah, a little later on, I too thought about making a primary out of a long string of MMC caps, but I thought that probably the L-field would do wierd things to the complicated shapes of the little cap plates, like maybe create eddy currents and concentrate a large current on a small area of the plats, blowing the caps. anyway, just musing. cheers, Wells Campbell wellscampbell@onebox.com Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Wed, 4 Sep 2002 12:38:55 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Wed, 04 Sep 2002 12:29:58 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: Re: OLTC idea... X-Mailing-List: archive/latest/2052 X-Loop: tesla@pupman.com Original poster: "K. C. Herrick by way of Terry Fritz " Wells, Terry & all from Ken Herrick- I've always thought that this kind of thing was a good idea: cause as much of the primary circuit's magnetic flux as possible to pass thru the secondary rather than go elsewhere. My s.s. system started out with 1 (equivalent) primary turn but I've increased that now to 3 in order to reduce the magnetizing current. I keep all the primary's current-carrying components (MOSFETs, capacitors) as close to the location of the actual conductors as possible. But I need to use discrete capacitors since mine are large electrolytics (driving an untuned primary). It seems to me that Terry's capacitors are indeed "part of the inductive loop". Their inductance comprises part of the total primary inductance and they appear to be physically oriented such that the flux from that inductance goes pretty much where the flux from the copper coil goes. I've made a paper-design of a spark-gap system in which the primary's multiple capacitors, and multiple spark gaps, are arrayed in a circle co-planar with a copper-tubing coil so as to constitute not only the "C" of the L-C primary but also one of the 6 turns of conductor. So far, alas, it's only on paper... Ken Herrick On Tue, 03 Sep 2002 21:49:27 -0600 "Tesla list" writes: > Original poster: "Terry Fritz" > > Hi Wells, > > I was originally thinking of having the primary caps as part of the > inductive loop. As it "turned out", the caps were brought outside > the > loop. I was afraid that the cap being "part" of the 4500Amp primary > may do > something unforseen. I don't "know" of anything bad, but I didn't > want to > take a chance and the thing sort of worked out to what it is now. I > think > Ken's coil may use this for his single loop primary? > > Cheers, > > Terry > > > At 08:30 PM 9/3/2002 -0700, you wrote: > >Hi Terry, all, > > > >I am writing with a kind of an oddball idea which I had a few years > ago, > >and actually made it work on my little desktop coil, and had > forgotten > >it completely until today as I was daydreaming...maybe it's a > concept > >that would have some use in the OLTC realm, who knows... > > > >Let me first take you back to the heyday of rolled poly caps and > Richard > >Quick gaps, about the time when the first little blue boxy-looking > phillips > >caps were being soldered together and all the "high power guys" > were > >scoffing at the idea of an MMC being used for anything but a little > coil...A > >post about rolled poly caps talked about reducing inductance in the > rolled > >caps by using strips of foil every turn or two as a terminal, so > that > >the charge didn't have to travel around and around the plate to get > to > >the terminal. > > > >well, I got to thinking, what if you could make a cap that had > about > >the inducance of a primary, wrapped around a tube which would go > around > >the secondary and serve as both the primary and cap in one unit-I > think > >I called it a capductor or incapacitator or something, and got some > copper > >foil and twisted one up. The way it worked was that each plate had > it's > >terminal at opposing ends, so that the charge had to travel in the > direction > >that contributed to the magnetic field instead of cancelling it > out. > >I wrapped the plate/poly/plate/poly stack around a tube which fit > around > >my secondary with about an inch of clearance, and was about 1/3 as > high > >as my secondary, with about 8 turns total. The gap and supply went > in > >parallel to the "incapacitator", and it resonated with itself. (I > know, > >hurts to think about, but basically the inductive properties and > the > >capacitive properties produced a unit that resonated at the same > frequency > >as my secondary, and served as a primary and cap in one). It > actually > >worked! I got the values so close on the first try that I was able > to > >tune with 3/4 turn of refrig. tubing, off axis. > > > >Anyway, my reasoning was that it would be the lowest loss > arrangement > >ever, because the energy wouldn't have to travel out of the > capacitor, > >into the primary, and back, but would just be rocking back and > forth > >along the plates of the incapacitator. > > > >I dunno, maybe you could construct a poly and copper plate cap that > would > >wrap around the base of the OLTC, and simply connect the IGBT > "brick" > >across the leads of the incapacitator? you would have to get the > values > >right in designing the thing, but that shouldn't be too hard, I did > it > >with wintesla. > > > >Anyway, just an idea, I thought it was a neat concept at the time, > but > >never got much farther than cobble-up. But it was neat seeing > "noodle > >theory" turn into reality :>). > > > >Does this sound like anything you could use? > > > >-- > >Wells Campbell > >wellscampbell@onebox.com > > > > > > > > > > Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Sun, 18 Aug 2002 11:52:26 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Sun, 18 Aug 2002 11:43:09 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: oltc inductor design X-Mailing-List: archive/latest/1235 X-Loop: tesla@pupman.com Original poster: "Steve Mach by way of Terry Fritz " Terry, Check out http://thayer.dartmouth.edu/other/inductor/qdgj.pdf for info on inductor gaps,losses,ect. I came across it while researching another project.The rest of the site is worth a look too. Also http://henry.fbe.fh-darmstadt.de/smps_e/ may be helpful. This is exciting stuff(watching the smoke roll from your ears,NOT the oltc !)unfolding in front of us. Who knows someday we may see a Tesla knockdown dragout between "OL TERRY" (not old, off line) and say 13M ! Keep the smoke in, Steve Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Tue, 13 Aug 2002 12:39:03 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Tue, 13 Aug 2002 12:28:54 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: OLTC Multi Primary X-Mailing-List: archive/latest/910 X-Loop: tesla@pupman.com Original poster: "Terry Fritz" Hello everyone, esp. those on the OLTC scene... Looking through hot-streamer.com/temp, whatever happened to the Multi primary idea? (hot-streamer.com/temp/OLTC_Multi_Primary.jpg) Too much coupling? Too Complicated, or too many priamry coils ( > 10 ) I think having each IGBT with its own cap is a great idea, i would have never thought of that! Keep up the good work! Hot-streamer.com/OLTC now exists, but is under construction. --------------------------------------- Jonathon Reinhart hot-streamer.com/jonathon Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Tue, 13 Aug 2002 13:49:47 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Tue, 13 Aug 2002 13:02:51 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: Re: OLTC Multi Primary X-Mailing-List: archive/latest/928 X-Loop: tesla@pupman.com Original poster: "Terry Fritz" Hi Jonathon, At 10:49 AM 8/13/2002 -0400, you wrote: >Hello everyone, esp. those on the OLTC scene... > >Looking through hot-streamer.com/temp, whatever happened to the Multi primary >idea? >(hot-streamer.com/temp/OLTC_Multi_Primary.jpg) >Too much coupling? Too Complicated, or too many priamry coils ( > 10 ) It just seems too complex and ten primary loops may reduce the inductance of the primary too much. "I" also worry that the voltages on each loop may not stay in sync with each other. It just had a few unknowns and no real reason to go that way. I am trying to keep everything as basic and simple as possible, pleanty of time later to make things complicated ;-)) Cheers, Terry > >I think having each IGBT with its own cap is a great idea, i would have never >thought of that! > >Keep up the good work! Hot-streamer.com/OLTC now exists, but is under >construction. > >--------------------------------------- >Jonathon Reinhart >hot-streamer.com/jonathon > Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Wed, 14 Aug 2002 06:34:40 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Wed, 14 Aug 2002 06:23:56 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: Re: OLTC Multi Primary X-Mailing-List: archive/latest/987 X-Loop: tesla@pupman.com Original poster: "Marry Krutsch by way of Terry Fritz " Hi All, I don't know whether or not the drawing/idea was mis-understood or not, but I'll explain the idea again. I discussed this with Terry a few weeks ago, and he thought that it was too complicated. I still don't think so, but then again, I'm not the one trying to build it and get it to work without smoke entering the picture ;-)). I also don't have the fancy computer modeling stuff that Terry has (I can't even imagine how much that aids in designing circuits). Anyway, the idea was not only for each transistor to have its own capacitor, but for each one to have its own complete tank circuit, identical to the others. The main point to this was keeping the resonant frequency in the "normal" TC range by keeping the Fres of each tank high, while keeping the total energy in all of the caps (tanks) high enough to do some good at low (120 BPS) break rates. That way, the secondary coil wouldn't need to have 0.5 Henries of inductance =:-0, and would therefor be less of a pain to build. Also, using this method, power-per-break can be increased without further lowering the operating frequency, if the coil is running directly from the line and not DC. The current consensus (I think) is that the prototype OLTC will run on DC. The idea was to wind all the "separate" primary coils into a bundle, like Litz wire, so that no one tank would see too much more kickback than the others, and so the secondary coil would "see" only one primary. Running at such a low frequency means that, using a "conventional" TC tank setup, you must lose either primary inductance, or capacitance. Each one has its inherant problems. The multiple tank circuit method allows you to in effect, lose neither one. I know that an IGBT is a little different from a sparkgap ;-)), but their function in the circuit is the same. Current sharing is less of a problem, since there are no transistors in parallel. The firing timing issue is the same as with the current setup. And, a problem with one circuit should not affect the others, so a catastophic "dominoe effect" failure would be less likely. The wire used in each tank would be much smaller than that used in a single larger one, so making and manipulating the setup would be easier. There were some other perks to this (I think), but I've forgotten them. I did some math, and worked out a coil that runs at 70kHz, with a TOTAL primary capacitance of 30uF. It has 10 tanks, each with a 3uF cap, and a 1.75 turn, 4.5" radius, 1.72 uH primary. The total energy stored at a peak voltage of 320 is 1.56 joules. The primary would in reality be 1 turn. The extra 0.75 is to account for off-axis inductance (tank wiring), and other stray effects. If anything, this should be lower. The secondary is 27.5" (wound), 2175 turns, and 6" in diameter. The toroid is a modest 6" by 20". Lastly, I should say that I'm sure that there are problems with this idea that I can't see, since I'm not know for my intelligence ;-)). So, I invite the gurus of TC'ing to pick this clean. I know I'll learn something from that. I also don't mean to question Terry's judgement. I wouldn't have mentioned this idea on the list, but since someone brought it up, I though I'd explain it. Terry is right in keeping things simple for the first try. This can be explored later (if at all). I left some stuff out, but I'm getting tired (it's 12:45 am, and I've got work tomorrow). Sorry for such a long post. I didn't intend for it to be that way ;-)). Thanks for reading, Winston K. Tesla list wrote: > > Original poster: "Terry Fritz" > > Hi Jonathon, > > At 10:49 AM 8/13/2002 -0400, you wrote: > >Hello everyone, esp. those on the OLTC scene... > > > >Looking through hot-streamer.com/temp, whatever happened to the Multi primary > >idea? > >(hot-streamer.com/temp/OLTC_Multi_Primary.jpg) > >Too much coupling? Too Complicated, or too many priamry coils ( > 10 ) > > It just seems too complex and ten primary loops may reduce the inductance > of the primary too much. "I" also worry that the voltages on each loop may > not stay in sync with each other. It just had a few unknowns and no real > reason to go that way. I am trying to keep everything as basic and simple > as possible, pleanty of time later to make things complicated ;-)) > > Cheers, > > Terry > > > > >I think having each IGBT with its own cap is a great idea, i would have never > >thought of that! > > > >Keep up the good work! Hot-streamer.com/OLTC now exists, but is under > >construction. > > > >--------------------------------------- > >Jonathon Reinhart > >hot-streamer.com/jonathon > > Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Wed, 14 Aug 2002 16:52:12 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Wed, 14 Aug 2002 16:43:01 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: Re: OLTC Multi Primary X-Mailing-List: archive/latest/1009 X-Loop: tesla@pupman.com Original poster: "Malcolm Watts by way of Terry Fritz " Hi Winston, On 14 Aug 2002, at 6:23, Tesla list wrote: > Original poster: "Marry Krutsch by way of Terry Fritz " > > Hi All, > > I don't know whether or not the drawing/idea was mis-understood or not, > but I'll explain the idea again. I discussed this with Terry a few > weeks ago, and he thought that it was too complicated. I still don't > think so, but then again, I'm not the one trying to build it and get it > to work without smoke entering the picture ;-)). I also don't have the > fancy computer modeling stuff that Terry has (I can't even imagine how > much that aids in designing circuits). > > Anyway, the idea was not only for each transistor to have its own > capacitor, but for each one to have its own complete tank circuit, > identical to the others. The main point to this was keeping the > resonant frequency in the "normal" TC range by keeping the Fres of each > tank high, while keeping the total energy in all of the caps (tanks) > high enough to do some good at low (120 BPS) break rates. That way, the > secondary coil wouldn't need to have 0.5 Henries of inductance =:-0, and > would therefor be less of a pain to build. If the primaries are bundled, the coupling between each would be close to 1. It might as well be a single conductor. The total inductance of the bundle would still be that of a single conductor. In effect, it reduces to Terry's multiple capacitor/switch arrangement. > Also, using this method, power-per-break can be increased without > further lowering the operating frequency, if the coil is running > directly from the line and not DC. The current consensus (I think) is > that the prototype OLTC will run on DC. > > The idea was to wind all the "separate" primary coils into a bundle, > like Litz wire, so that no one tank would see too much more kickback > than the others, and so the secondary coil would "see" only one > primary. Running at such a low frequency means that, using a > "conventional" TC tank setup, you must lose either primary inductance, > or capacitance. Each one has its inherant problems. The multiple tank > circuit method allows you to in effect, lose neither one. I know that > an IGBT is a little different from a sparkgap ;-)), but their function > in the circuit is the same. > > Current sharing is less of a problem, since there are no transistors in > parallel. The firing timing issue is the same as with the current > setup. And, a problem with one circuit should not affect the others, so > a catastophic "dominoe effect" failure would be less likely. The wire > used in each tank would be much smaller than that used in a single > larger one, so making and manipulating the setup would be easier. There > were some other perks to this (I think), but I've forgotten them. But the coupling constant between the bundled conductors *is* almost 1. The separate primary circuits will not be separate at all and each will see the effects generated by its mates. Regards, Malcolm > I did some math, and worked out a coil that runs at 70kHz, with a TOTAL > primary capacitance of 30uF. It has 10 tanks, each with a 3uF cap, and > a 1.75 turn, 4.5" radius, 1.72 uH primary. The total energy stored at a > peak voltage of 320 is 1.56 joules. The primary would in reality be 1 > turn. The extra 0.75 is to account for off-axis inductance (tank > wiring), and other stray effects. If anything, this should be lower. > The secondary is 27.5" (wound), 2175 turns, and 6" in diameter. The > toroid is a modest 6" by 20". > > Lastly, I should say that I'm sure that there are problems with this > idea that I can't see, since I'm not know for my intelligence ;-)). So, > I invite the gurus of TC'ing to pick this clean. I know I'll learn > something from that. I also don't mean to question Terry's judgement. > I wouldn't have mentioned this idea on the list, but since someone > brought it up, I though I'd explain it. Terry is right in keeping > things simple for the first try. This can be explored later (if at > all). I left some stuff out, but I'm getting tired (it's 12:45 am, and > I've got work tomorrow). > > Sorry for such a long post. I didn't intend for it to be that way > ;-)). Thanks for reading, > Winston K. > > > Tesla list wrote: > > > > Original poster: "Terry Fritz" > > > > Hi Jonathon, > > > > At 10:49 AM 8/13/2002 -0400, you wrote: > > >Hello everyone, esp. those on the OLTC scene... > > > > > >Looking through hot-streamer.com/temp, whatever happened to the Multi > primary > > >idea? > > >(hot-streamer.com/temp/OLTC_Multi_Primary.jpg) > > >Too much coupling? Too Complicated, or too many priamry coils ( > 10 ) > > > > It just seems too complex and ten primary loops may reduce the inductance > > of the primary too much. "I" also worry that the voltages on each loop may > > not stay in sync with each other. It just had a few unknowns and no real > > reason to go that way. I am trying to keep everything as basic and simple > > as possible, pleanty of time later to make things complicated ;-)) > > > > Cheers, > > > > Terry > > > > > > > >I think having each IGBT with its own cap is a great idea, i would have > never > > >thought of that! > > > > > >Keep up the good work! Hot-streamer.com/OLTC now exists, but is under > > >construction. > > > > > >--------------------------------------- > > >Jonathon Reinhart > > >hot-streamer.com/jonathon > > > > > > > Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Wed, 14 Aug 2002 17:06:22 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Wed, 14 Aug 2002 17:01:50 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: Re: OLTC Multi Primary X-Mailing-List: archive/latest/1011 X-Loop: tesla@pupman.com Original poster: "Terry Fritz" Hi Winston, At 12:49 AM 8/14/2002 -0700, you wrote: >Hi All, > > I don't know whether or not the drawing/idea was mis-understood or not, >but I'll explain the idea again. I discussed this with Terry a few >weeks ago, and he thought that it was too complicated. I still don't >think so, but then again, I'm not the one trying to build it and get it >to work without smoke entering the picture ;-)). I also don't have the >fancy computer modeling stuff that Terry has (I can't even imagine how >much that aids in designing circuits). > > Anyway, the idea was not only for each transistor to have its own >capacitor, but for each one to have its own complete tank circuit, >identical to the others. The main point to this was keeping the >resonant frequency in the "normal" TC range by keeping the Fres of each >tank high, while keeping the total energy in all of the caps (tanks) >high enough to do some good at low (120 BPS) break rates. That way, the >secondary coil wouldn't need to have 0.5 Henries of inductance =:-0, and >would therefor be less of a pain to build. I think if they were really close together, they would just act as a single big block of copper. The inside turns may be shielded by the outer turns in the bundle. I also do not really want the turns isolated from each other. With either the caps or primary inductors in parallel, I have a way of forcing everything to stay in phase. If they were separate, a misfire where two were to go 180 degrees out of phase could be "odd". It may work fine, but there were just to many unknowns for me to go that way right now. A future thing. > > Also, using this method, power-per-break can be increased without >further lowering the operating frequency, if the coil is running >directly from the line and not DC. The current consensus (I think) is >that the prototype OLTC will run on DC. It is synced to the AC line. Sort of DC pulses in a resonant charging mode. Pretty much locked in at 120 BPS. > > The idea was to wind all the "separate" primary coils into a bundle, >like Litz wire, so that no one tank would see too much more kickback >than the others, and so the secondary coil would "see" only one >primary. Running at such a low frequency means that, using a >"conventional" TC tank setup, you must lose either primary inductance, >or capacitance. Each one has its inherant problems. The multiple tank >circuit method allows you to in effect, lose neither one. I know that >an IGBT is a little different from a sparkgap ;-)), but their function >in the circuit is the same. > > Current sharing is less of a problem, since there are no transistors in >parallel. The firing timing issue is the same as with the current >setup. And, a problem with one circuit should not affect the others, so >a catastophic "dominoe effect" failure would be less likely. The wire >used in each tank would be much smaller than that used in a single >larger one, so making and manipulating the setup would be easier. There >were some other perks to this (I think), but I've forgotten them. > > I did some math, and worked out a coil that runs at 70kHz, with a TOTAL >primary capacitance of 30uF. It has 10 tanks, each with a 3uF cap, and >a 1.75 turn, 4.5" radius, 1.72 uH primary. The total energy stored at a >peak voltage of 320 is 1.56 joules. The primary would in reality be 1 >turn. The extra 0.75 is to account for off-axis inductance (tank >wiring), and other stray effects. If anything, this should be lower. >The secondary is 27.5" (wound), 2175 turns, and 6" in diameter. The >toroid is a modest 6" by 20". > > Lastly, I should say that I'm sure that there are problems with this >idea that I can't see, since I'm not know for my intelligence ;-)). It may work perfectly fine. I really don't know. In this case, I just wanted to spend time on other things so I went with something I knew would work. Once it works, then everyone can figure out ways to improve it. >So, >I invite the gurus of TC'ing to pick this clean. I know I'll learn >something from that. I also don't mean to question Terry's judgement. >I wouldn't have mentioned this idea on the list, but since someone >brought it up, I though I'd explain it. Terry is right in keeping >things simple for the first try. This can be explored later (if at >all). I left some stuff out, but I'm getting tired (it's 12:45 am, and >I've got work tomorrow). No problem at all :-)) If it works, there will be all kinds of new and fancy improvements added. But right now, the key is getting it to work at all... Besides, I already made the primary, so it's too late :o)) Cheers, Terry > > Sorry for such a long post. I didn't intend for it to be that way >;-)). Thanks for reading, >Winston K. > > Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Tue, 13 Aug 2002 12:48:31 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Tue, 13 Aug 2002 12:32:29 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: OLTC page X-Mailing-List: archive/latest/917 X-Loop: tesla@pupman.com Original poster: "by way of Terry Fritz " Terry Fritz Says: >I should make a nice web page and explain all the details in a nice format. >But I could spend my time doing that or building the coil. So... this is all >you get :o)) Ok, I wanted to be a part of this, so I did: http://hot-streamer.com/OLTC/ remeber, I started at 12:30 PM last night, so it still is under construction. any tips, suggestions, flames...etc greatly appreciated. Thanks again Terry, and good luck to everyone on the OLTC scene... --------------------------------------- Jonathon Reinhart hot-streamer.com/jonathon Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Thu, 15 Aug 2002 11:48:00 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Thu, 15 Aug 2002 11:34:30 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: OLTC Page update X-Mailing-List: archive/latest/1043 X-Loop: tesla@pupman.com Original poster: "by way of Terry Fritz " Hi everyone, OLTC Page is looking a little better, and seems like a lot of you are visiting it (I'm still getting the counter to work). I could use a little help with how it works, someone has to know more than I do: The 240 VAC Mains is rectified in the OLTC Main Controller. Am I right that it comes out 340 VDC? anyways, the tank capacitor is resonantly charged at about 540 volts. now here's where I get confused. I think, because you use a current transformer, once the charging current either goes up to a certain level, or down to a certain level, it causes the IGBTs (which stands for what? something transistor) to close, just like a regular spark gap does in disruptive coils. You then 'quench' the circuit by opening the IGBTs. This traps most (90%?) of the energy in the Secondary Coil. http://hot-streamer.com/OLTC Thats about it, Im not sure about the small details. Also, Terry was kind enough to put all the OLTC related stuff in the hot-streamer.com/OLTC/files directory. (***Terry, I renamed it, because the stuff wasn't really temporary***) Hope I'm working for a good cause here, Jonathon REinhart Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Sun, 11 Aug 2002 15:33:39 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Sun, 11 Aug 2002 15:30:06 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: OLTC posts X-Mailing-List: archive/latest/775 X-Loop: tesla@pupman.com Original poster: "Terry Fritz" Hi All, In case you missed any... I put all the recent posts about Off-Line Tesla Coils into a text file at: http://hot-streamer.com/temp/Off-LineTeslaCoils(OLTC).txt I left it a text file (94k) so you can just read it in the browser. Cheers, Terry Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Fri, 30 Aug 2002 09:18:16 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Fri, 30 Aug 2002 09:12:07 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: Re: OLTC primary loss measurement X-Mailing-List: archive/latest/1724 X-Loop: tesla@pupman.com Original poster: "tesla by way of Terry Fritz " Greetings Terry et al I wonder if it's practical to actually measure the IGBT lossses directly 1) Operate coil in still air environment 2) Run near full power until in thermal equilibrium 3) Do the sums for the heatsink thermal d(temperature) from its published thermal resistance to air. 4) Thus directly derive power driving the thermal rise. 5) Compare with power I/P and volia Best Ted L in NZ Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Fri, 30 Aug 2002 12:04:21 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Fri, 30 Aug 2002 11:57:43 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: Re: OLTC primary loss measurement X-Mailing-List: archive/latest/1726 X-Loop: tesla@pupman.com Original poster: "Jim Lux by way of Terry Fritz " Or, because you probably don't know all the thermal resistances and masses involved, do a replacement energy approach... Run the coil, measure the temperature rise at some convenient place. Then, arrange to have the parts dissipate DC power (which is easy to measure as I * V) to match the temperature rise. Something as simple as a variable voltage source to bias the devices partly on, with a DC source (like a big battery) across the "switch" terminals (C to E, I imagine)... You don't care about the losses in the battery or wire, because you can measure the current anywhere in the loop (Kirchoff's current law helps here...) and use a Hi-Z volt meter to measure the voltage drop across the devices (at whatever convenient boundary you want to use). At 09:12 AM 8/30/2002 -0600, you wrote: >Original poster: "tesla by way of Terry Fritz " > > >Greetings Terry et al > >I wonder if it's practical to actually measure the IGBT lossses directly >1) Operate coil in still air environment >2) Run near full power until in thermal equilibrium >3) Do the sums for the heatsink thermal d(temperature) from its published >thermal resistance to air. >4) Thus directly derive power driving the thermal rise. >5) Compare with power I/P and volia >Best >Ted L in NZ Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Fri, 30 Aug 2002 14:07:28 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Fri, 30 Aug 2002 14:02:55 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: Re: OLTC primary loss measurement X-Mailing-List: archive/latest/1733 X-Loop: tesla@pupman.com Original poster: "tesla by way of Terry Fritz " Few Further thoughts on last post re this: 1) The only thermal resistance you need to know is heatsink to air if you measure heatsink temp. This is normally published for each heatsink type 2) You can reduce time to reach equilibrium if you preheat the heatsink with a hairdrier. (you need to have a feeling for this as to how much to preheat it) 3) Smaller heatsinking would much reduce time to reach equilibrium if that is a problem. Good Luck Ted L in NZ Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Fri, 30 Aug 2002 14:06:55 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Fri, 30 Aug 2002 14:04:01 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: Re: OLTC primary loss measurement X-Mailing-List: archive/latest/1734 X-Loop: tesla@pupman.com Original poster: "tesla by way of Terry Fritz " Another thought I think you can get stick on liquid crystal thermometer strips so you can "see" the temperature of a device. With the thermal time constants involved however the thermal probe that comes with you DMM could be used I suspect, attach after the system has been switched off. Best Ted L in NZ Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Fri, 30 Aug 2002 14:14:30 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Fri, 30 Aug 2002 14:12:26 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: Re: OLTC primary loss measurement X-Mailing-List: archive/latest/1735 X-Loop: tesla@pupman.com Original poster: "Terry Fritz" Hi Ted, It is a little hard in that you should really measure the change in temperature over time. Such as how long it takes to raise the temperature 10C. There is a lot of noise there but a little filtered and isolated LM35 IC based circuit could do that. Another problem is that there is not a lot of heat there. About 22 watts in the IGBT array. The caps actually have higher dissipation. I think the primary coil is very low indeed. I can just "ring down" the bare primary and find the resistance from the time it takes the wave to get to 10% as John Couture's book explains. I will do this... However, I have another giant loss problem on my hands in the secondary that dwarfs primary losses... Cheers, Terry At 01:26 AM 8/31/2002 +1200, you wrote: >Greetings Terry et al > >I wonder if it's practical to actually measure the IGBT lossses directly >1) Operate coil in still air environment >2) Run near full power until in thermal equilibrium >3) Do the sums for the heatsink thermal d(temperature) from its published >thermal resistance to air. >4) Thus directly derive power driving the thermal rise. >5) Compare with power I/P and volia >Best >Ted L in NZ > Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Fri, 30 Aug 2002 15:33:13 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Fri, 30 Aug 2002 15:30:01 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: Re: OLTC primary loss measurement X-Mailing-List: archive/latest/1739 X-Loop: tesla@pupman.com Original poster: "tesla by way of Terry Fritz " Greetings Terry et al Understand your comments Clearly priority in performance terms is the big losses first and since it is clear that IGBT losses do not dominate the idea is probably moot. But it is actually an easy measurement to make. Just one point, I do not agree with the notion of how long it takes to raise the temperature being the appropriate method. This is a brings in thermal mass, along with driving power and thermal resistance heatsink to air. Its like trying to measure voltage given C and time constant when the ohms law of thermal systems is more direct. The driving electrical power is fully defined by the difference between ambient and heatsink temperature at EQUILIBRIUM. Delta Temp/Thermal Resistance (sink to air)=Watts Good luck and we look forward to more installments of the OLTC story when you have the time Rgds Ted L in NZ Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Fri, 30 Aug 2002 15:34:20 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Fri, 30 Aug 2002 15:31:16 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: Re: OLTC primary loss measurement X-Mailing-List: archive/latest/1740 X-Loop: tesla@pupman.com Original poster: "Jim Lux by way of Terry Fritz " At 02:02 PM 8/30/2002 -0600, you wrote: >Original poster: "tesla by way of Terry Fritz " > > >Few Further thoughts on last post re this: > >1) The only thermal resistance you need to know is heatsink to air if you >measure heatsink temp. This is normally published for each heatsink type But that number is only a "design guide", used for sizing the sink in the first place, not an actual measured or reliable number. A huge amount of things can affect the sink<>ambient resistance.. small amounts of air movement (as from thermal gradients) dramatically reduce the thermal resistance. If you think electromagnetic stuff is complex, it's nothing compared to heat transfer, where the transfer medium is non-linear, has varying flow regimes (turbulent/laminar), and all sorts of other weird effects. Putting it in a big box (to reduce the effect of external air currents) and doing a power replacement calorimetric measurement would be your only hope >2) You can reduce time to reach equilibrium if you preheat the heatsink with >a hairdrier. (you need to have a feeling for this as to how much to preheat >it) > >3) Smaller heatsinking would much reduce time to reach equilibrium if that >is a problem. > >Good Luck >Ted L in NZ Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Fri, 30 Aug 2002 20:06:56 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Fri, 30 Aug 2002 20:02:54 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: Re: OLTC primary loss measurement X-Mailing-List: archive/latest/1763 X-Loop: tesla@pupman.com Original poster: "tesla by way of Terry Fritz " Greetings Jim et el I think you rasie a very valid point regarding the variability actual thermal resistance of the sink to air figure and this would certainly lead to significant errors. I do suspect that heatsink degC/watt figures are for a set of defined conditions however and would apply if they were accurately reproduced in Terry's lab (and thats probably not possible) I have a friend who has worked professionally assessing heatsink efficiency and modest setup or environmental changes do lead to significant changes in degC/watt for a given sink. But in controlled environments ie stll air and limited room gradients good repeatability is possible in his experience. A simple method (short of full calorimetric measurements) to get more accurate results might be to run pure DC thru the IGBT array and to calibrate the degrees centigrade per watt figure for the system. This could be done at about the same power loss level expected for the operating tesla. While the system was still warm the operating tesla system could then be substiuted for the DC. If draughts are excluded and orientations of elements are not changed reasonable accuracy could be obtained. All this said as the IGBT losses are believed to be small compared with other losses the matter may not be worth too much effort. Rgds Ted L in NZ > >Few Further thoughts on last post re this: > > > >1) The only thermal resistance you need to know is heatsink to air if you > >measure heatsink temp. This is normally published for each heatsink type > > > But that number is only a "design guide", used for sizing the sink in the > first place, not an actual measured or reliable number. A huge amount of > things can affect the sink<>ambient resistance.. small amounts of air > movement (as from thermal gradients) dramatically reduce the thermal > resistance. If you think electromagnetic stuff is complex, it's nothing > compared to heat transfer, where the transfer medium is non-linear, has > varying flow regimes (turbulent/laminar), and all sorts of other weird effects. > > Putting it in a big box (to reduce the effect of external air currents) and > doing a power replacement calorimetric measurement would be your only hope Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Sat, 31 Aug 2002 12:20:49 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Sat, 31 Aug 2002 11:59:53 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: Re: OLTC primary loss measurement X-Mailing-List: archive/latest/1786 X-Loop: tesla@pupman.com Original poster: "Jim Lux by way of Terry Fritz " > > I have a friend who has worked professionally assessing heatsink efficiency > and modest setup or environmental changes do lead to significant changes in > degC/watt for a given sink. > But in controlled environments ie stll air and limited room gradients good > repeatability is possible in his experience. Exactly..the sink temperature/watt relation is generally pretty repeatable (even in normal lab environment with the a/c blowing), which is why the DC replacement technique should work pretty well (at least to 5%, probably better) (hey, if it works for RF measurements in a precision power meter, it can work here, right?) > > A simple method (short of full calorimetric measurements) to get more > accurate results might be to run pure DC thru the IGBT array and to > calibrate the degrees centigrade per watt figure for the system. This could > be done at about the same power loss level expected for the operating tesla. Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Mon, 2 Sep 2002 17:05:34 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Mon, 02 Sep 2002 16:51:36 -0600 From: "Tesla list" To: "Paul" Cc: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: Re: OLTC primary loss measurement X-Mailing-List: archive/latest/1922 X-Loop: tesla@pupman.com Original poster: "Terry Fritz" Hi Paul, I was not able to find any time to work on this yeasterday. But today... The 20,40,60... Volts I gave is a "metered" voltage. The actual firing voltage is twice that number. If Rpri = 2 x pi x F x L / Q Vfire Qpri Rpri 40 4.7 0.0197 80 7.3 0.0127 120 10.0 0.00927 160 12.1 0.00766 200 14.0 0.00662 So the graph looks like: http://hot-streamer.com/temp/OLTC09-02-01.gif If one uses your equations below which seem to fit very well: http://hot-streamer.com/temp/OLTC09-02-02.gif Looks like I can expect a Q of 21.4 at 4.3mOhms for Rpri. Vds Seems high here at 8 volts. Probably not too surprising given that so many terms are at work in the "real" system. However, if we pump 2000 amps peak into the system, the loss for Vds is: 8*2081 = 16648 watts peak While the loss for Rpri is: 2081^2 x 0.00662 = 28668 watts The system peak power is about 200*2081 = 416kW Of course, 416000 /(16648 + 28668) = Q = 9.18 here in my guess work. Off by the square root of two... I will have to think about if Rpri or Vds has any reason to be so high. Have to think about cap and Lpri second order resonances and other horrific things... Probably still have enough drive there in any case, but I just like to know exactly "why"... Cheers, Terry BTW - I'll copy the list in case others are interested in just nitty gritty details... At 03:36 PM 9/1/2002 +0100, you wrote: >I ran the primary alone as shown: >> >> http://hot-streamer.com/temp/OLTC08-31-06.jpg >> >>I ran at 5 input voltages of 20,40,60,80, and 100 volts as read on the >>meter. On 120 VAC that can go up to 150 volts and at 240 vac in it goes up >>to 300 volts. So I still have 3x the voltage to go. I didn't go higher >>here since I am not sure where the "power" is going? >> >> The files are at: >> http://hot-streamer.com/temp/OLTC/8-31PriD-1/ > >> I ran at 5 input voltages of 20,40,60,80, and 100 volts > >TEK00000: 20 volts >PK FREQ kHz (Error +/-) Q FACTOR (Error +/-) LEVEL > 1 37.198 (0.01%,2Hz) 4.66 (22.33%, 1.0) -6.3dB > 2 105.675 (0.01%,5Hz) 19.57 (37.56%, 7.3) -29.4dB > >TEK00001: 40 volts >PK FREQ kHz (Error +/-) Q FACTOR (Error +/-) LEVEL > 1 36.534 (0.01%,2Hz) 7.27 (15.79%, 1.1) -5.2dB > 2 108.118 (0.01%,6Hz) 30.73 (53.12%,16.3) -30.0dB > >TEK00002: 60 volts >PK FREQ kHz (Error +/-) Q FACTOR (Error +/-) LEVEL > 1 36.471 (0.01%,2Hz) 9.95 (13.28%, 1.3) -4.9dB > 2 108.834 (0.01%,5Hz) 44.21 (63.17%,27.9) -29.2dB > >TEK00003: 80 volts >PK FREQ kHz (Error +/-) Q FACTOR (Error +/-) LEVEL > 1 36.534 (0.01%,2Hz) 12.12 (13.28%, 1.6) -4.5dB > 2 108.976 (0.01%,5Hz) 50.65 (63.17%,32.0) -30.4dB > >TEK00004: 100 volts >PK FREQ kHz (Error +/-) Q FACTOR (Error +/-) LEVEL > 1 36.590 (0.01%,2Hz) 14.04 (11.17%, 1.6) -4.4dB > 2 108.971 (0.01%,5Hz) 48.13 (63.17%,30.4) -30.7dB > > >Note the low level of harmonic content at all voltages, which >suggests that non-linearity within the RF cycle isn't a problem, >ie your diodes are turning on/off ok, etc. > >Summarising > > V Qpri > > 20 4.7 > 40 7.3 > 60 10.0 > 80 12.1 >100 14.0 > >If power dissipated is given by Ip^2Rp + Vds * Ip >where Rp is effective R of coil+caps and Vds is volts drop >across IGBTs, then > > Energy dissipated per cycle = Ip * (Ip*Rp + Vds)/F > >and > > Energy stored = Lp*Ip^2 > >then [fixed font] > > Q = 2 * pi * F * Lp * Ip^2 > ---------------------- > Ip * (Ip*Rp + Vds) > > > = 2 * pi * F * Lp * Ip = 2 * pi * F * Lp > -------------------- --------------- > Ip*Rp + Vds Rp + Vds/Ip > >If Ip = Vp/(2*pi*F*Lp) >then > Q = 2 * pi * F * Lp > --------------------- > Rp + Vds*2*pi*F*Lp/Vp > >and > > 1/Q = Rp + Vds * 1 > --------- -- > 2*pi*F*Lp Vp > > >If we plot your data as 1/Q against 1/Vp, and extrapolate, >we estimate a Q tending towards 30 at high voltage, which >means that Rp will be around 0.003 ohms. The slope gives >a Vds of around 3.5 volts. > >I guess you're coming up with the difficulty of getting a >high Q in a very low impedance resonator. >-- >Paul Nicholson, >-- Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Mon, 2 Sep 2002 22:05:51 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Mon, 02 Sep 2002 21:34:53 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: Re: OLTC primary loss measurement X-Mailing-List: archive/latest/1969 X-Loop: tesla@pupman.com Original poster: "Bert Hickman by way of Terry Fritz " Hi Terry, Did you ever make an estimates of capacitor ESR?? Gotta' believe those flimsy leads also add a fair amount of series resistance in the primary circuit... -- Bert -- -- Bert Hickman Stoneridge Engineering "Electromagically" (TM) Shrunken Coins! http://www.teslamania.com Tesla list wrote: > > Original poster: "Terry Fritz" > > Hi Paul, > > I was not able to find any time to work on this yeasterday. But today... > > The 20,40,60... Volts I gave is a "metered" voltage. The actual firing > voltage is twice that number. > > If Rpri = 2 x pi x F x L / Q > > Vfire Qpri Rpri > > 40 4.7 0.0197 > 80 7.3 0.0127 > 120 10.0 0.00927 > 160 12.1 0.00766 > 200 14.0 0.00662 > > So the graph looks like: > > http://hot-streamer.com/temp/OLTC09-02-01.gif > > If one uses your equations below which seem to fit very well: > > http://hot-streamer.com/temp/OLTC09-02-02.gif > > Looks like I can expect a Q of 21.4 at 4.3mOhms for Rpri. > > Vds Seems high here at 8 volts. Probably not too surprising given that so > many terms are at work in the "real" system. However, if we pump 2000 amps > peak into the system, the loss for Vds is: > > 8*2081 = 16648 watts peak > > While the loss for Rpri is: > > 2081^2 x 0.00662 = 28668 watts > > The system peak power is about 200*2081 = 416kW > > Of course, 416000 /(16648 + 28668) = Q = 9.18 here in my guess work. Off > by the square root of two... > > I will have to think about if Rpri or Vds has any reason to be so high. > Have to think about cap and Lpri second order resonances and other horrific > things... Probably still have enough drive there in any case, but I just > like to know exactly "why"... > > Cheers, > > Terry Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Sun, 11 Aug 2002 10:49:45 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Sun, 11 Aug 2002 10:35:29 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: OLTC Thoughts X-Mailing-List: archive/latest/749 X-Loop: tesla@pupman.com Original poster: "Wall Richard Wayne by way of Terry Fritz " Terry, Here are some other OLTC design thoughts. Your TC primary, 47 mF cap(s) and IGBT switch(s) form a large LC tank. Once fired this thank will have huge oscillatory currents. What are the reverse stand off voltages of the IGBTs? Hopefully they have a built in protection diode. But, I would not depend on this small diode, if it exists, for protection. Which brings up another point. Richard Hull's H2 thyratron magnifier, by necessity, quenched at the first zero crossing of the wave form. So only the positive half of the energy cycle was passed to the primary. While a very interesting design, it is not a spectacular performer, if one measures performance by spark length. It's a phenomenal research device though. You may consider adding free running back diodes across your IGBTs for protection and for a full one cycle energy transfer. Have you calculated the resonate oscillatory frequency of the primary tank without the switches? Also consider moving the switch(s) outside the LC tank altogether to allow the tank to oscillate freely and transfer even more energy before you electronically quench it. I'll leave these design thoughts up to your fertile electronics imagination. RWW > Hi All, > > To update the IGBT current sharing in the OLTC... > > We have say 2000 amps and ten 200 amp IGBTs to switch it. There is a > problem in how to be sure the IGBTs share that current equally. If one > IGBT takes like 400 amps, it is a "bad" thing! The circuit looks like this: > > http://hot-streamer.com/temp/OLTC8-10-01.gif > > Basically, you slam all those IGBTs on with very low inductance, impedance > balanced "buss work". Done well, it is simple and easy, once some nasty > details are worked out. I have put a lot of thought about how I would do > this for the OLTC. Lots of worry over the 10nH wire bonds inside the IGBTs > and stuff... However, I guess that was all wasted now since the solution > is...: > > http://hot-streamer.com/temp/OLTC8-10-02.gif > > Yep! We have ten independent primary caps too. If we hook them up like > this, the cap's impedance naturally hard balances the current to the IGBTs. > It is just a done deal, "painfully" simple... nothing can go wrong. It's > gotta work. Even if just one IGBT turns on I "think" it self protects... > If one stays out, it self protects... (the frequency is wrong, but who > cares...) > > This solution to current sharing of the OLTC's IGBTs is so beautiful, it > makes me wanna cry... > > Cheers, > > Terry > > --- Richard Wayne Wall --- rwall@ix.netcom.com Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Sun, 11 Aug 2002 11:29:23 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Sun, 11 Aug 2002 11:26:48 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: Re: OLTC Thoughts X-Mailing-List: archive/latest/755 X-Loop: tesla@pupman.com Original poster: "Terry Fritz" Hi Richard, At 11:16 AM 8/11/2002 -0400, you wrote: >Terry, > >Here are some other OLTC design thoughts. > >Your TC primary, 47 mF cap(s) and IGBT switch(s) form a large LC tank. >Once fired this thank will have huge oscillatory currents. What are the >reverse stand off voltages of the IGBTs? 900 volts. They make higher but these are really cheap. I ran a bunch of models studying what might happen to the voltage and where they run at and they should be very safe. I am also putting in some big MOVs to catch any over voltage swings at 750V. here is a pic of a transient and how the coils handles it: http://hot-streamer.com/temp/OLTC-08-07-2.gif >Hopefully they have a built in >protection diode. But, I would not depend on this small diode, if it >exists, for protection. Which brings up another point. Richard Hull's H2 >thyratron magnifier, by necessity, quenched at the first zero crossing of >the wave form. So only the positive half of the energy cycle was passed to >the primary. While a very interesting design, it is not a spectacular >performer, if one measures performance by spark length. It's a phenomenal >research device though. You may consider adding free running back diodes >across your IGBTs for protection and for a full one cycle energy transfer. The IGBTs have big powerful anti-parallel diodes in them already ;-)) >Have you calculated the resonate oscillatory frequency of the primary tank >without the switches? Also consider moving the switch(s) outside the LC >tank altogether to allow the tank to oscillate freely and transfer even >more energy before you electronically quench it. I'll leave these design >thoughts up to your fertile electronics imagination. They are fairly well outside it now. I have to watch out for induced currents from the primary on control wiring. Cheers, Terry > >RWW > >> Hi All, >> >> To update the IGBT current sharing in the OLTC... >> >> We have say 2000 amps and ten 200 amp IGBTs to switch it. There is a >> problem in how to be sure the IGBTs share that current equally. If one >> IGBT takes like 400 amps, it is a "bad" thing! The circuit looks like >this: >> >> http://hot-streamer.com/temp/OLTC8-10-01.gif >> >> Basically, you slam all those IGBTs on with very low inductance, impedance >> balanced "buss work". Done well, it is simple and easy, once some nasty >> details are worked out. I have put a lot of thought about how I would do >> this for the OLTC. Lots of worry over the 10nH wire bonds inside the >IGBTs >> and stuff... However, I guess that was all wasted now since the solution >> is...: >> >> http://hot-streamer.com/temp/OLTC8-10-02.gif >> >> Yep! We have ten independent primary caps too. If we hook them up like >> this, the cap's impedance naturally hard balances the current to the >IGBTs. >> It is just a done deal, "painfully" simple... nothing can go wrong. It's >> gotta work. Even if just one IGBT turns on I "think" it self protects... >> If one stays out, it self protects... (the frequency is wrong, but who >> cares...) >> >> This solution to current sharing of the OLTC's IGBTs is so beautiful, it >> makes me wanna cry... >> >> Cheers, >> >> Terry >> >> > > > >--- Richard Wayne Wall >--- rwall@ix.netcom.com > > > Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Sun, 11 Aug 2002 14:41:00 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Sun, 11 Aug 2002 14:36:31 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: Re: OLTC Thoughts X-Mailing-List: archive/latest/767 X-Loop: tesla@pupman.com Original poster: "Terry Fritz" Hi Richard, At 04:14 PM 8/11/2002 -0400, you wrote: >Terry, > >> The IGBTs have big powerful anti-parallel diodes in them already ;-)) > >Excellent, do you know the speed (Reverse Recovery time) of these diodes? >If they're too slow you may need to add supplemental fast diodes. Your >fast CE MOVs or snubbers are also good ideas. The data sheet is at: http://hot-streamer.com/temp/irg4pf50wd.pdf > >> >> >Have you calculated the resonate oscillatory frequency of the primary >tank >> >without the switches? Also consider moving the switch(s) outside the LC >> >tank altogether to allow the tank to oscillate freely and transfer even >> >more energy before you electronically quench it. I'll leave these design >> >thoughts up to your fertile electronics imagination. >> >> They are fairly well outside it now. > >Your schematic places the IGBTs right in the LC tank circuit. See >http://hot-streamer.com/temp/OLTC8-10-01.gif et subsequent. Yes, the IGBTs act just like a normal spark gap. The coils basic function is just like that of any disruptive coil. > >Another consideration is that with ten IGBTs and ten 4.7 mF caps, not only >does turn on have to be right on the money, BUT turn off has to also be >exactly the same for all IGBTs. It can really be very sloppy. If one turns on 1.3uS early, no problem. The key is that the current in the tank is pretty slow to come up due to the tank inductor. The IGBT's will easily outrun it. >Post firing, as the tank oscillates and it >is also charged by the PS, differences in IGBT turn off timing will affect >residual charge imparted on each 4.7 mF cap. I can actually leave them charged negative for even higher power. http://www.pupman.com/listarchives/2002/August/msg00424.html > >What is your proposed IGBT firing rate and dwell time? 120BPS and around 130uS. The firing rate is automatically controlled and the dwell is from a 555 timer. http://www.pupman.com/listarchives/2002/August/msg00391.html http://www.pupman.com/listarchives/2002/August/msg00414.html > >RWW > >--- Richard Wayne Wall >--- rwall@ix.netcom.com > > > Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Sun, 11 Aug 2002 14:40:56 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Sun, 11 Aug 2002 14:36:58 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: Re: OLTC Thoughts X-Mailing-List: archive/latest/766 X-Loop: tesla@pupman.com Original poster: "Wall Richard Wayne by way of Terry Fritz " Terry, > The IGBTs have big powerful anti-parallel diodes in them already ;-)) Excellent, do you know the speed (Reverse Recovery time) of these diodes? If they're too slow you may need to add supplemental fast diodes. Your fast CE MOVs or snubbers are also good ideas. > > >Have you calculated the resonate oscillatory frequency of the primary tank > >without the switches? Also consider moving the switch(s) outside the LC > >tank altogether to allow the tank to oscillate freely and transfer even > >more energy before you electronically quench it. I'll leave these design > >thoughts up to your fertile electronics imagination. > > They are fairly well outside it now. Your schematic places the IGBTs right in the LC tank circuit. See http://hot-streamer.com/temp/OLTC8-10-01.gif et subsequent. Another consideration is that with ten IGBTs and ten 4.7 mF caps, not only does turn on have to be right on the money, BUT turn off has to also be exactly the same for all IGBTs. Post firing, as the tank oscillates and it is also charged by the PS, differences in IGBT turn off timing will affect residual charge imparted on each 4.7 mF cap. What is your proposed IGBT firing rate and dwell time? RWW --- Richard Wayne Wall --- rwall@ix.netcom.com Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Sun, 11 Aug 2002 14:48:41 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Sun, 11 Aug 2002 14:45:58 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: Re: OLTC Thoughts X-Mailing-List: archive/latest/768 X-Loop: tesla@pupman.com Original poster: "Wall Richard Wayne by way of Terry Fritz " List, For those who mentioned it, the most KISS and effective way to increase OLTC voltage is to tune the primary tank circuit. With good resonate tuning, high Q and HV resonate rise, high voltages can be captured in the tank cap. Then the tank circuit can be fired at higher voltage. RWW --- Richard Wayne Wall --- rwall@ix.netcom.com Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Sun, 11 Aug 2002 18:56:59 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Sun, 11 Aug 2002 18:53:00 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: Re: OLTC Thoughts X-Mailing-List: archive/latest/790 X-Loop: tesla@pupman.com Original poster: "Antonio Carlos M. de Queiroz by way of Terry Fritz " Tesla list wrote: > > Original poster: "Wall Richard Wayne by way of Terry Fritz " > ... > Richard Hull's H2 > thyratron magnifier, by necessity, quenched at the first zero crossing of > the wave form. So only the positive half of the energy cycle was passed to > the primary. While a very interesting design, it is not a spectacular > performer, if one measures performance by spark length. It's a phenomenal > research device though. This is quite strange. A Tesla coil, or a magnifier, can't operate correctly without at least two polarity reversals in the primary current. If the current is interrupted after the first half-cycle, only a small fraction of the primary energy is transferred to the secondary. Where is this magnifier described? Antonio Carlos M. de Queiroz Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Sun, 11 Aug 2002 21:44:39 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Sun, 11 Aug 2002 21:32:40 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: Re: OLTC Thoughts X-Mailing-List: archive/latest/796 X-Loop: tesla@pupman.com Original poster: "Eddie Burwell by way of Terry Fritz " At 02:36 PM 8/11/02 -0600, you wrote: >Original poster: "Wall Richard Wayne by way of Terry Fritz " > >Terry, > >> The IGBTs have big powerful anti-parallel diodes in them already ;-)) > >Excellent, do you know the speed (Reverse Recovery time) of these diodes? >If they're too slow you may need to add supplemental fast diodes. Your >fast CE MOVs or snubbers are also good ideas. > >--- Richard Wayne Wall >--- rwall@ix.netcom.com > Reverse recovery shouldn't be a problem. The IGBT will be forward conducting as soon as the current reverses except for the last cycle where the IGBT is turned off to "quench the gap". So the diode might have a true reverse recovery 120 times per second. I say might because that will depend if you quench at a notch or not. The bad thing about the reverse diode is that if you quench at the first notch the diode will tend to rectify the voltage coupled back to the primary and recharge the caps with the energy leached from the secondary. Of course if the streamer has already eaten most of the energy it's no big deal. Eddie Burwell Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Sun, 11 Aug 2002 21:42:44 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Sun, 11 Aug 2002 21:35:33 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: Re: OLTC Thoughts X-Mailing-List: archive/latest/801 X-Loop: tesla@pupman.com Original poster: "Wall Richard Wayne by way of Terry Fritz " Antonio, > > Richard Hull's H2 > > thyratron magnifier, by necessity, quenched at the first zero crossing of > > the wave form. So only the positive half of the energy cycle was passed to > > the primary. While a very interesting design, it is not a spectacular > > performer, if one measures performance by spark length. It's a phenomenal > > research device though. > > This is quite strange. A Tesla coil, or a magnifier, can't operate > correctly without at least two polarity reversals in the primary > current. > If the current is interrupted after the first half-cycle, only a small > fraction of the primary energy is transferred to the secondary. > Where is this magnifier described? Yes, it does seem quite strange. Even though with only one half cycle there is still some energy transfer. The coil does spark and has a peculiar harsh audible hum. But, overall performance is inhibited. I posted this point because Terry's OLTC will have similar very quick quenching which may inhibit expected performance. I have no doubt he will figure out timing problems though. A fly back diode on each switch will get it through one complete cycle. Richard Hull designed and built this thyratron maggey. He has demonstrated it at the TCBOR Teslathon. I'm sure many on this list have seen this coil in action. Richard is no longer on this list, but I'm sure he would advise you where it's written up. RWW Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Sun, 11 Aug 2002 22:56:53 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Sun, 11 Aug 2002 22:50:28 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: Re: OLTC Thoughts X-Mailing-List: archive/latest/811 X-Loop: tesla@pupman.com Original poster: "Bert Hickman by way of Terry Fritz " Richard, Antonio, and all, I've seen Richard Hull's thyratron powered coil in operation, and as Rich Wall indicated, it only began to do an energy transfer from primary to secondary, firing for 1/2 cycle, and then shutting off. It used a small hydrogen (H2) thyratron (type 3C45) with no reverse conduction diode. So, when fired, it conducted for the first half cycle, then shut off at the next current zero crossing. There were many discussions about using hydrogen diodes or high current high voltage rectifiers to conduct the primary's reverse current since most thyratrons don't do this very gracefully or for very long. For a complete energy transfer, multiple triggers would be necessary, one for each positive half cycle until the primary to secondary energy transfer completed. The beauty of the H2 thyratron switch was that is could quench "on a dime", permitting tightly controlled quenching experiments. By triggering only once, only a relatively small amount of energy was actually transferred to the secondary. By using the MOSFETS to provide forward primary current, and then using a high current diode to conduct in the reverse direction, Terry's OLTC offers the capability to simply, yet tightly, control the degree of quenching. Best regards, -- Bert -- -- Bert Hickman Stoneridge Engineering "Electromagically" Shrunken Coins! http://www.teslamania.com Tesla list wrote: > > Original poster: "Wall Richard Wayne by way of Terry Fritz " > > Antonio, > > > > Richard Hull's H2 > > > thyratron magnifier, by necessity, quenched at the first zero crossing > of > > > the wave form. So only the positive half of the energy cycle was > passed to > > > the primary. While a very interesting design, it is not a spectacular > > > performer, if one measures performance by spark length. It's a > phenomenal > > > research device though. > > > > This is quite strange. A Tesla coil, or a magnifier, can't operate > > correctly without at least two polarity reversals in the primary > > current. > > If the current is interrupted after the first half-cycle, only a small > > fraction of the primary energy is transferred to the secondary. > > Where is this magnifier described? > > Yes, it does seem quite strange. Even though with only one half cycle > there is still some energy transfer. The coil does spark and has a > peculiar harsh audible hum. But, overall performance is inhibited. I > posted this point because Terry's OLTC will have similar very quick > quenching which may inhibit expected performance. I have no doubt he will > figure out timing problems though. A fly back diode on each switch will > get it through one complete cycle. > > Richard Hull designed and built this thyratron maggey. He has demonstrated > it at the TCBOR Teslathon. I'm sure many on this list have seen this coil > in action. Richard is no longer on this list, but I'm sure he would advise > you where it's written up. > > RWW Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Sun, 11 Aug 2002 23:05:47 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Sun, 11 Aug 2002 23:01:03 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: Re: OLTC Thoughts X-Mailing-List: archive/latest/812 X-Loop: tesla@pupman.com Original poster: "Terry Fritz" Hi, There has also been discursion off list about the fact that when I turn the IGBTs off, the reverse diodes will still be active. I "think" it will not be a problem at all. For the energy to get back into the primary, the primary circuit has to be tuned to Fo. With just the anti-parallel diodes in the primary circuit, the "tuning" will be devastated and the primary should simply not be able to re-absorb the power. Thus, the energy will be trapped in the secondary. This is just a theory still. I have nick named it the "Winston effect" since Winston brought it up to me ;-) Also, if one uses the individual IGBTs to tune the coil. The "off" cap will just charge negative through the anti-parallel diode and fall out of the circuit. If it does not work, Dave's CEEC configuration would, but at twice the power loss (not a big deal) and twice the cost in IGBTs. Hopefully, the single IGBT solution will work. Cheers, Terry At 11:09 PM 8/11/2002 -0500, you wrote: >Richard, Antonio, and all, > >I've seen Richard Hull's thyratron powered coil in operation, and as >Rich Wall indicated, it only began to do an energy transfer from primary >to secondary, firing for 1/2 cycle, and then shutting off. It used a >small hydrogen (H2) thyratron (type 3C45) with no reverse conduction >diode. So, when fired, it conducted for the first half cycle, then shut >off at the next current zero crossing. There were many discussions about >using hydrogen diodes or high current high voltage rectifiers to conduct >the primary's reverse current since most thyratrons don't do this very >gracefully or for very long. For a complete energy transfer, multiple >triggers would be necessary, one for each positive half cycle until the >primary to secondary energy transfer completed. The beauty of the H2 >thyratron switch was that is could quench "on a dime", permitting >tightly controlled quenching experiments. By triggering only once, only >a relatively small amount of energy was actually transferred to the >secondary. > >By using the MOSFETS to provide forward primary current, and then using >a high current diode to conduct in the reverse direction, Terry's OLTC >offers the capability to simply, yet tightly, control the degree of >quenching. > >Best regards, > >-- Bert -- >-- >Bert Hickman >Stoneridge Engineering >"Electromagically" Shrunken Coins! >http://www.teslamania.com > > >Tesla list wrote: >> >> Original poster: "Wall Richard Wayne by way of Terry Fritz >" >> >> Antonio, >> >> > > Richard Hull's H2 >> > > thyratron magnifier, by necessity, quenched at the first zero crossing >> of >> > > the wave form. So only the positive half of the energy cycle was >> passed to >> > > the primary. While a very interesting design, it is not a spectacular >> > > performer, if one measures performance by spark length. It's a >> phenomenal >> > > research device though. >> > >> > This is quite strange. A Tesla coil, or a magnifier, can't operate >> > correctly without at least two polarity reversals in the primary >> > current. >> > If the current is interrupted after the first half-cycle, only a small >> > fraction of the primary energy is transferred to the secondary. >> > Where is this magnifier described? >> >> Yes, it does seem quite strange. Even though with only one half cycle >> there is still some energy transfer. The coil does spark and has a >> peculiar harsh audible hum. But, overall performance is inhibited. I >> posted this point because Terry's OLTC will have similar very quick >> quenching which may inhibit expected performance. I have no doubt he will >> figure out timing problems though. A fly back diode on each switch will >> get it through one complete cycle. >> >> Richard Hull designed and built this thyratron maggey. He has demonstrated >> it at the TCBOR Teslathon. I'm sure many on this list have seen this coil >> in action. Richard is no longer on this list, but I'm sure he would advise >> you where it's written up. >> >> RWW > Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Mon, 12 Aug 2002 08:35:51 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Mon, 12 Aug 2002 08:03:45 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: Re: OLTC Thoughts X-Mailing-List: archive/latest/818 X-Loop: tesla@pupman.com Original poster: "by way of Terry Fritz " In a message dated 8/11/02 8:55:34 PM Eastern Daylight Time, tesla@pupman.com writes: > > > ... > > Richard Hull's H2 > > thyratron magnifier, by necessity, quenched at the first zero crossing of > > the wave form. So only the positive half of the energy cycle was passed to > > the primary. While a very interesting design, it is not a spectacular > > performer, if one measures performance by spark length. It's a phenomenal > > research device though. > > This is quite strange. A Tesla coil, or a magnifier, can't operate > correctly without at least two polarity reversals in the primary > current. > If the current is interrupted after the first half-cycle, only a small > fraction of the primary energy is transferred to the secondary. > Where is this magnifier described? > > Antonio Carlos M. de Queiroz Antonio, It's likely that an incomplete amount of energy was transfered in Richard's thyratron TC, as you suggest. This probably severely limited the performance. There's an article about it in a TCBA issue, but he doesn't discuss the power transfer issue, I don't think. Some have speculated that the driver coupling was only about k = 0.3 or less, which would require a number of cycles to fully transfer the energy of course. Richard was planning to do further work using back-to-back thyratrons, or a parallel diode to pass the reverse current, but he moved on to other projects. Cheers, John Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Mon, 12 Aug 2002 18:22:25 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Mon, 12 Aug 2002 18:08:32 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: Re: OLTC Thoughts X-Mailing-List: archive/latest/859 X-Loop: tesla@pupman.com Original poster: "Malcolm Watts by way of Terry Fritz " Hi Richard, Terry, On 11 Aug 2002, at 21:35, Tesla list wrote: > Original poster: "Wall Richard Wayne by way of Terry Fritz " > > Antonio, > > > > Richard Hull's H2 > > > thyratron magnifier, by necessity, quenched at the first zero crossing > of > > > the wave form. So only the positive half of the energy cycle was > passed to > > > the primary. While a very interesting design, it is not a spectacular > > > performer, if one measures performance by spark length. It's a > phenomenal > > > research device though. > > > > This is quite strange. A Tesla coil, or a magnifier, can't operate > > correctly without at least two polarity reversals in the primary > > current. > > If the current is interrupted after the first half-cycle, only a small > > fraction of the primary energy is transferred to the secondary. > > Where is this magnifier described? > > Yes, it does seem quite strange. Even though with only one half cycle > there is still some energy transfer. The coil does spark and has a > peculiar harsh audible hum. But, overall performance is inhibited. I > posted this point because Terry's OLTC will have similar very quick > quenching which may inhibit expected performance. I have no doubt he will > figure out timing problems though. A fly back diode on each switch will > get it through one complete cycle. *Some* IGBTs come with a body diode tailored to match the normal conductive channel's characteristics. Regards, Malcolm > Richard Hull designed and built this thyratron maggey. He has demonstrated > it at the TCBOR Teslathon. I'm sure many on this list have seen this coil > in action. Richard is no longer on this list, but I'm sure he would advise > you where it's written up. > > RWW > > > > > Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Mon, 12 Aug 2002 18:22:25 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Mon, 12 Aug 2002 18:09:04 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: Re: OLTC Thoughts X-Mailing-List: archive/latest/865 X-Loop: tesla@pupman.com Original poster: "Malcolm Watts by way of Terry Fritz " Hi Terry, On 11 Aug 2002, at 23:01, Tesla list wrote: > Original poster: "Terry Fritz" > > Hi, > > There has also been discursion off list about the fact that when I turn the > IGBTs off, the reverse diodes will still be active. I "think" it will not > be a problem at all. For the energy to get back into the primary, the > primary circuit has to be tuned to Fo. With just the anti-parallel diodes > in the primary circuit, the "tuning" will be devastated and the primary > should simply not be able to re-absorb the power. Thus, the energy will be > trapped in the secondary. A voltage will be induced in the primary as the secondary continues to oscillate. They key is whether that voltage matches the C-E voltage as the power supply charges the caps back up. If it doesn't on the first cycle of secondary oscillation after the IGBT drive has been shut off, it should provide a clean break. Some years ago I did all this with a bank of MOSFETs to investigate some of the Corum's claims. My primary voltage was a rather modest 30V but the secondary succeeded in generating thousands. The important point is that shutting the gate drive off seemed to work despite the body diodes in the FETs. I found no evidence to support the Corum's claims of "coherence" BTW ;) Regards, malcolm > This is just a theory still. I have nick named it the "Winston effect" > since Winston brought it up to me ;-) > > Also, if one uses the individual IGBTs to tune the coil. The "off" cap > will just charge negative through the anti-parallel diode and fall out of > the circuit. > > If it does not work, Dave's CEEC configuration would, but at twice the > power loss (not a big deal) and twice the cost in IGBTs. Hopefully, the > single IGBT solution will work. > > Cheers, > > Terry > > > At 11:09 PM 8/11/2002 -0500, you wrote: > >Richard, Antonio, and all, > > > >I've seen Richard Hull's thyratron powered coil in operation, and as > >Rich Wall indicated, it only began to do an energy transfer from primary > >to secondary, firing for 1/2 cycle, and then shutting off. It used a > >small hydrogen (H2) thyratron (type 3C45) with no reverse conduction > >diode. So, when fired, it conducted for the first half cycle, then shut > >off at the next current zero crossing. There were many discussions about > >using hydrogen diodes or high current high voltage rectifiers to conduct > >the primary's reverse current since most thyratrons don't do this very > >gracefully or for very long. For a complete energy transfer, multiple > >triggers would be necessary, one for each positive half cycle until the > >primary to secondary energy transfer completed. The beauty of the H2 > >thyratron switch was that is could quench "on a dime", permitting > >tightly controlled quenching experiments. By triggering only once, only > >a relatively small amount of energy was actually transferred to the > >secondary. > > > >By using the MOSFETS to provide forward primary current, and then using > >a high current diode to conduct in the reverse direction, Terry's OLTC > >offers the capability to simply, yet tightly, control the degree of > >quenching. > > > >Best regards, > > > >-- Bert -- > >-- > >Bert Hickman > >Stoneridge Engineering > >"Electromagically" Shrunken Coins! > >http://www.teslamania.com > > > > > >Tesla list wrote: > >> > >> Original poster: "Wall Richard Wayne by way of Terry Fritz > >" > >> > >> Antonio, > >> > >> > > Richard Hull's H2 > >> > > thyratron magnifier, by necessity, quenched at the first zero crossing > >> of > >> > > the wave form. So only the positive half of the energy cycle was > >> passed to > >> > > the primary. While a very interesting design, it is not a spectacular > >> > > performer, if one measures performance by spark length. It's a > >> phenomenal > >> > > research device though. > >> > > >> > This is quite strange. A Tesla coil, or a magnifier, can't operate > >> > correctly without at least two polarity reversals in the primary > >> > current. > >> > If the current is interrupted after the first half-cycle, only a small > >> > fraction of the primary energy is transferred to the secondary. > >> > Where is this magnifier described? > >> > >> Yes, it does seem quite strange. Even though with only one half cycle > >> there is still some energy transfer. The coil does spark and has a > >> peculiar harsh audible hum. But, overall performance is inhibited. I > >> posted this point because Terry's OLTC will have similar very quick > >> quenching which may inhibit expected performance. I have no doubt he will > >> figure out timing problems though. A fly back diode on each switch will > >> get it through one complete cycle. > >> > >> Richard Hull designed and built this thyratron maggey. He has demonstrated > >> it at the TCBOR Teslathon. I'm sure many on this list have seen this coil > >> in action. Richard is no longer on this list, but I'm sure he would advise > >> you where it's written up. > >> > >> RWW > > > > > Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Sun, 4 Aug 2002 22:17:45 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Sun, 04 Aug 2002 22:04:18 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: OLTC update X-Mailing-List: archive/latest/392 X-Loop: tesla@pupman.com Original poster: "Terry Fritz" Hi All, I have been working pretty hard on my Off-Line Tesla Coil project. Mostly ordering things and running computer models to check things out. But I am starting to get some "real" stuff going too ;-) All still looks well... I built the 240VAC controller today. http://hot-streamer.com/temp/OLTCcontFRONT.jpg http://hot-streamer.com/temp/OLTCcontBACK.jpg http://hot-streamer.com/temp/OLTCcontSCHEM.gif http://hot-streamer.com/temp/OLTCcontTOP1.jpg http://hot-streamer.com/temp/OLTCcontTOP2.jpg It came in at 4 pounds 15 ounces instead of two pounds ;-)) Hey, that is still lighter than just a big variac knob like you "big iron" guys use :o))) It is designed for about 1+kVA but it could do about 4kVA if it had to. All heavy duty stuff that can take a big "hit" if things go... "bad"... Really not much to it. Just a nice safe way to control 240 VAC into a Tesla coil. I have not had a chance to test it yet since the dryer outlet is being used for the stupid dryer ;-)) I got to use the Brother P-Touch label maker a lot :-)) I am also collecting parts for the IGBT switch: http://hot-streamer.com/temp/P8040005.jpg I guess it does not look like much yet :-) Actually, only the 10 IGBTs in the tube, the bag of MOVs, and the section of heat sink I sliced out right quick in the band saw are for the IGBT spark gap. The box and protoboard are for the IGBT firing control. Hopefully it will look cool pretty soon ;-) I was going to get the milling machine working on the heat sink tonight, but getting too late... I found that I need to fire all the IGBTs within 1.3uS of each other. Dave Sharpe clued me into the Toshiba TLP250 driver chip (just another DigiKey part...) which will be great! I still need to work a lot on the SYNC timing stuff... The IGBTs will be paralleled together with less than 15nH of inductance. More than that and their phase angles start to get goofy. It is really very simple in practice... I guy at work gave me a big beat up 300 amp brick but I was surprised it was rated at "only" 600 amps peak :-p Seems the big bricks are not designed well for really high peak currents like my project will need. No matter, since many small IGBTs are like 1/10th the cost... I wonder if an extreme Tesla coil use of IGBTs will teach the "big boys" a few trick like the MMC caps did ;-)) The bricks are really not designed all that well... they are mostly worried with slow speed high thermal dissipation stuff... I think I will go with a primary coil of three 14 inch diameter copper tubing loops (1/2 inch diameter tubing) spaced 2.5 inches apart. Everyone can find this "stuff" and the IGBTs can evenly push current into such a structure. Tuning will probably be through a variable number if primary caps. Might need a multi-taped resonant inductor too, but I'll see... A lot depends on the inductance of the cap and switch structures... Maybe I can have an adjustable inductor in there somehow... Talking like 300nH... Still thinking... It is all brand new territory here... OLTCs are sort of complex from a theoretical point of view, but the hardware is really very very simple once the gnarly details are figured out. Hopefully, it might actually work!! I am trying to keep it really simple so others could easily make one. There are fancy improvements and stuff I am neglecting in the name of "keep it simple"... We will see.... Cheers, Terry Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Sun, 4 Aug 2002 22:57:43 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Sun, 04 Aug 2002 22:53:42 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: OLTC update X-Mailing-List: archive/latest/396 X-Loop: tesla@pupman.com Original poster: "Terry Fritz" Hi All, > > >I built the 240VAC controller today. > > http://hot-streamer.com/temp/OLTCcontFRONT.jpg > > I just wanted to mention that the clothes finally got dry and I was able to test it. It works perfectly :-))) http://hot-streamer.com/temp/P8040010.jpg Cheers, Terry Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Mon, 5 Aug 2002 19:07:28 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Mon, 05 Aug 2002 18:58:34 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: Re: OLTC update X-Mailing-List: archive/latest/449 X-Loop: tesla@pupman.com Original poster: "David Sharpe by way of Terry Fritz " Terry Very nice looking controller. Will e-mail PDF of TLP250 datasheet to you either tonight or tomorrow... Can post on Hotstreamer. All the application info is there. Regards Dave Sharpe, TCBOR Chesterfield, VA. USA Tesla list wrote: > Original poster: "Terry Fritz" > > Hi All, > > > > > > >I built the 240VAC controller today. > > > > http://hot-streamer.com/temp/OLTCcontFRONT.jpg > > > > > > I just wanted to mention that the clothes finally got dry and I was able to > test it. It works perfectly :-))) > > http://hot-streamer.com/temp/P8040010.jpg > > Cheers, > > Terry Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Tue, 6 Aug 2002 22:15:52 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Tue, 06 Aug 2002 21:56:11 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: OLTC update X-Mailing-List: archive/latest/507 X-Loop: tesla@pupman.com Original poster: "Terry Fritz" Hi All, I got the IGBT's mounted to a heat sink and the primary coil made up. http://hot-streamer.com/temp/P8050014.jpg http://hot-streamer.com/temp/P8050015.jpg http://hot-streamer.com/temp/P8060016.jpg http://hot-streamer.com/temp/P8060019.jpg The primary is three parallel 1/2 inch copper pipes 14 inches in diamater, spaced 2.5 inches apart (all center to center). Still needs copper iny and outy plates, caps, and the drive electronics before it really starts to look like something cool. But it's getting there ;-) I hope the milling machine was not cheating :-)) They don't make things better, they just make things faster ;-)) Cheers, Terry Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Wed, 7 Aug 2002 19:32:17 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Wed, 07 Aug 2002 19:25:29 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: OLTC update X-Mailing-List: archive/latest/548 X-Loop: tesla@pupman.com Original poster: "Terry Fritz" Hi All, I think I figured out a super simple, easy, and cheap way to control the firing timing of my OLTC project. In this diagram: http://hot-streamer.com/temp/OLTC-08-07.gif I simply put a 0.1 ohm resistor (Rsense) inline with the charging circuit. When the current across the resistor goes negative it happens to be the perfect time to fire the IGBT array. The cap, resistors and diode (a 555 timer in real life) will control the ~130uS pulse width to give first notch quenching and all. Here are the major waveforms: http://hot-streamer.com/temp/OLTC-08-07-1.gif The timing circuit automatically seeks the most powerful mode and is very stable and reliable (at least on the computer ;-)) More importantly, such a circuit reacts very well to odd faults like this: http://hot-streamer.com/temp/OLTC-08-07-2.gif I was thinking of all kinds of fancy things and ways to run the coil's rather critical IGBT timing but they all had their problems, especially if things we not going just right. This new circuit is only a 0.1 ohm resistor, an op-amp, a 555 timer, and a driver chip to run the TLP250 IGBT drivers. What I thought would be the most messy part of the project to figure out, suddenly appears to be all done :-)) If this circuit and method work, it is a major breakthrough!! No more major technical stuff to figure out now. Just have to build it and see if it really works... Cheers, Terry Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Thu, 8 Aug 2002 12:31:26 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Thu, 08 Aug 2002 12:29:06 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: OLTC update X-Mailing-List: archive/latest/571 X-Loop: tesla@pupman.com Original poster: "Terry Fritz" Hi All, I drew up schematics for the timing control and IGBT gate drives. http://hot-streamer.com/temp/OLTC-TimingControl.gif http://hot-streamer.com/temp/OLTC-IGBTdrive.gif Not much to it ;-)) I'll just get a $3 current transformer from DigiKey to detect the current, run the output to a comparator to trigger a 555 timer and it's done. ;-) A current transformer provides isolation which is pretty handy in this case. Close to the IGBTs, I will have a the gate drive to push current into and out of all their gates. The TLP250s are opto isolators too so hopefully there will not be too much odd current running around. Might get tricky having electronics near a 2500 amp coil and 200,000 volt RF streamers running about ;-)) I'll have to try and keep things perpendicular to the big current loop. Cheers, Terry ================== Hi All, I think I figured out a super simple, easy, and cheap way to control the firing timing of my OLTC project. In this diagram: http://hot-streamer.com/temp/OLTC-08-07.gif I simply put a 0.1 ohm resistor (Rsense) inline with the charging circuit. When the current across the resistor goes negative it happens to be the perfect time to fire the IGBT array. The cap, resistors and diode (a 555 timer in real life) will control the ~130uS pulse width to give first notch quenching and all. Here are the major waveforms: http://hot-streamer.com/temp/OLTC-08-07-1.gif The timing circuit automatically seeks the most powerful mode and is very stable and reliable (at least on the computer ;-)) More importantly, such a circuit reacts very well to odd faults like this: http://hot-streamer.com/temp/OLTC-08-07-2.gif I was thinking of all kinds of fancy things and ways to run the coil's rather critical IGBT timing but they all had their problems, especially if things we not going just right. This new circuit is only a 0.1 ohm resistor, an op-amp, a 555 timer, and a driver chip to run the TLP250 IGBT drivers. What I thought would be the most messy part of the project to figure out, suddenly appears to be all done :-)) If this circuit and method work, it is a major breakthrough!! No more major technical stuff to figure out now. Just have to build it and see if it really works... Cheers, Terry Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Thu, 8 Aug 2002 20:26:10 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Thu, 08 Aug 2002 20:06:07 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: OLTC update X-Mailing-List: archive/latest/579 X-Loop: tesla@pupman.com Original poster: "Terry Fritz" Hi All, Today I explored ways to raise the OLTCs resonant frequency and increase the power. I found that I could go to a smaller 28.2uF primary cap (6 x 4.7uF) which would raise the resonant frequency to around 35kHz. So, maybe I will only need "one" mile of secondary wire :-) Here is the schematic: http://hot-streamer.com/temp/OLTC8-8-01.gif Here is something interesting about power! Since the quenching is electronically controlled and we are using resonant charging, we can turn the IGBTs off any time we like. Such as, when the caps are at a far negative voltage: http://hot-streamer.com/temp/OLTC8-8-05.gif What is stunning here, is that this gives us an effective firing voltage of 1018 volts while still staying reasonably in the safe region for 900 volt IGBTs! 1080 volts, 28,2uF, 120BPS... That is a coil primary system power of 1973 watts (16.4 joules per bang)!! Assuming a 90% coil efficiency, that "suggests" a streamer length of over seven feet!! However, there is a problem with the primary current: http://hot-streamer.com/temp/OLTC8-8-04.gif Looks like about 4500 amps peak =:O One would have to parallel up about 25 IGBTs. Not impossible or that expensive... I will not go this high in power for this coil (yet :o)) since I want some pretty good safety margins during 1st explosion... I mean "light" :-)) But really, the only change would be another pound of IGBTs and heat sinks for another $75. It is bazaar what you can do when things are all electronically controlled. I have a little more confidence in the models at 25kHz. They predict a 400kV peak output voltage with about a 500uS ringdown: http://hot-streamer.com/temp/OLTC8-8-03.gif No problems there ;-)) Although, I imagine getting hit with a coil at that frequency and power would not be fun... The system charging current is very tame with no surprises: http://hot-streamer.com/temp/OLTC8-8-02.gif This is interesting. Here is the AC line voltage and current into the system: http://hot-streamer.com/temp/OLTC8-8-06.gif No need for line filters or PFC caps :-)) I am think this coil will be very electrically quiet compared to the spark gap types. There really are not any terrible RFI generators in it except the streamers. Remember that the IGBT "main gap" gives off no real sound, heat, or light (at least, not more than once :o)) There is a slight "clicking" sound as 2000+ amps pulse through it and maybe 20 to 30 watts of heat, but that's it... System complexity is still very low. I am a bit worried that one may need a scope to check things in such a coil during construction, but I'll try to make it "just work" without any fancy stuff. Protection against faults is fairly good but only "real" testing can verify that... The theory may be "new" but it is much simpler than a conventional coil. There just isn't much hardware to it. System weight is also very low. There are two transformers. The current sense CT, but it is less than an inch square ;-) There will have to be an AC resonant inductor that will probably be about 4 pounds. I could, and may, use a small variac for testing, but the inductors value will never change normally, so it could be a simple fixed or tapped inductor. I have a variac core (4 pounds) and some smaller ones that would probably work. I was trying to sneak by without using any iron stuff ;-)) However, the "iron" weighs only 3% of what a 15/120 NST, SRSG motor and big variac does (160 pounds!) Of course, the super seven foot arc version would weigh "nothing" compared to a pig, 25 amp variac, controller, and an arc welder :o))) I will guess the whole thing will be about 25 pounds with most of the weight in the secondary and top terminal. The secondary will probably be like a 12 x 48 inch Sonotube. The top terminal will be a big as possible to help push that frequency down. Cost also seems low. The secondary and top terminal are big and conventional. Probably blow $50 there. The controller is almost nothing to $100 if you make a fancy one like I did. The electronics is maybe $40 with nice die cast boxes. $30 just in power cords and the dryer plug. "stuff" is probably another $50. Caps and IGBTs are anybody's guess. I'll just say they are about $5 each if you look around. Probably $100 total. So that adds up to... $370 Probably could do it for $250. Of course, "extra" IGBTs can add up, but at least things are pretty well isolated so "failures" are contained in just that part. Insuring reliability of the IGBTs needs to be the big priority once it is working. Not really much else that could fail... Three areas of concern are: 1. Primary circuit resistance and loss. 28.2uF at 25kHz as a reactance of 0.226 ohm. Not much room for a lot of extra resistance there!! I am trying for a primary circuit resistance of about 0.01 ohm. That is really low, but the primary circuit does resemble a big copper short ;-)) This actually goes right along with a primary inductance of only ~750nH! 2. Control, faults, and the unexpected... The "computers" say it will work ;-)) But there are a lot of things that can go wrong between theory and reality. I think the big basics are solid, but there certainly may be some "technical" problems that will need work. 3. The IGBTs. Currents of thousands of amps and many hundreds of volts... Current sharing... If there is anyway for it to fail, it certainly will. I "think" I have things covered, but I can use pretty light fuses to save the parts for analysis if they don't. I think if one IGBT "goes away", the rest will be safe. No too bad really but at these powers and this level of "experimentation", blown IGBTs are expected till the bugs are worked out. Of course, this all only exists in hard drives and dreams at the moment, but parts are coming in ;-)) Many thanks for everyone's ideas and thoughts on this, I have used them all!! Cheers, Terry Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Thu, 8 Aug 2002 23:32:16 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Thu, 08 Aug 2002 23:25:39 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: Re: OLTC update X-Mailing-List: archive/latest/593 X-Loop: tesla@pupman.com Original poster: "Eddie Burwell by way of Terry Fritz " Terry, Sound's like your pretty pump on this. I for one won't miss the weight of a NST! You could add some electrolytics and make a doubler (or rectify 220V) and then use an inductor to resonantly charge the primary cap at a frequency other than 60 hz. This would also double the voltage on the cap again. Then add some switch timing mischief.... Eddie Burwell Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Fri, 9 Aug 2002 23:41:31 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Fri, 09 Aug 2002 23:20:05 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: Re: OLTC update X-Mailing-List: archive/latest/649 X-Loop: tesla@pupman.com Original poster: "B2 by way of Terry Fritz " Hi Terry, Would it be easier to build a secondary that couples to a higher harmonic of the primary? Cheers, Barry Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Sat, 10 Aug 2002 19:45:54 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Sat, 10 Aug 2002 19:38:22 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: OLTC update X-Mailing-List: archive/latest/730 X-Loop: tesla@pupman.com Original poster: "Terry Fritz" Hi All, I have verified two import things the computer models predicted (apparently very well ;-)) I tested my primary coil today and it measures 439.5nH. So you "can" make a big single turn primary with less then 500nH inductance ;-)) That is critical for getting a high top voltage since Vo = ~1/2 SQRT (Ls/Lp). A lower Lp also allows higher operating frequency and a lower inductance secondary (which is already pretty high at about 500+mH). More importantly, I measured the coupling to my present big coil secondary at k=0.125!! I am not sure anyone realized that a single turn primary could have a high coupling like that! That is, of course, key for this thing to work. http://hot-streamer.com/temp/P8100020.jpg I used the simple (with nice test equipment) method on page 14-11 of John's "Tesla coil Construction Guide". A few weeks ago, I just happened to punch the single turn primary case into Mark R.'s program and was stunned the coupling was that high. That was a key factor that started this whole thing... Apparently, the coupling "really" is that good! These may seem like odd technical points, but they pretty much insure the OLTC will work. Just a matter of details now. In another note. I think I figured out how to insure that the IGBTs share current perfectly evenly!! No fancy stuff needed at all. I just thought of it like 15 seconds ago so let me think on it *:-)) It would be "tooooo" simple... Eliminates some rather critical IGBT mounting stuff... I also need some way to verify the very low loss of the primary circuit but I think I need the IGBTs and all running first since the loss is like 0.03 ohm and not at all easy to test. Probably need to test that for real but at low power... Back to work now ;-) Cheers, Terry Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Sat, 10 Aug 2002 21:48:28 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Sat, 10 Aug 2002 21:43:50 -0600 From: "Tesla list" To: tesla@pupman.com Cc: "David Sharpe" X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: OLTC update X-Mailing-List: archive/latest/736 X-Loop: tesla@pupman.com Original poster: "Terry Fritz" Hi All, To update the IGBT current sharing in the OLTC... We have say 2000 amps and ten 200 amp IGBTs to switch it. There is a problem in how to be sure the IGBTs share that current equally. If one IGBT takes like 400 amps, it is a "bad" thing! The circuit looks like this: http://hot-streamer.com/temp/OLTC8-10-01.gif Basically, you slam all those IGBTs on with very low inductance, impedance balanced "buss work". Done well, it is simple and easy, once some nasty details are worked out. I have put a lot of thought about how I would do this for the OLTC. Lots of worry over the 10nH wire bonds inside the IGBTs and stuff... However, I guess that was all wasted now since the solution is...: http://hot-streamer.com/temp/OLTC8-10-02.gif Yep! We have ten independent primary caps too. If we hook them up like this, the cap's impedance naturally hard balances the current to the IGBTs. It is just a done deal, "painfully" simple... nothing can go wrong. It's gotta work. Even if just one IGBT turns on I "think" it self protects... If one stays out, it self protects... (the frequency is wrong, but who cares...) This solution to current sharing of the OLTC's IGBTs is so beautiful, it makes me wanna cry... Cheers, Terry Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Sat, 10 Aug 2002 21:48:28 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Sat, 10 Aug 2002 21:44:09 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: RE: OLTC update X-Mailing-List: archive/latest/737 X-Loop: tesla@pupman.com Original poster: "Jeff W. Parisse by way of Terry Fritz " Terry, I agree that single turn primary coupling is counterintuitive. Bill Wysock's 13M magnifier uses a single turn primary and has the characteristic tight pri/sec coupling found on most magnifier designs. Interesting. I Love the threads that result from your "pet" projects... (remember the strobe?). ;-) Since we (TCML) coin the phrases that are used ad nauseam, I wanted to offer my 2 cents (worth less here) on the "off line" term. Off line implies that it's "off line", not working, not ready... Perhaps, transformer-less, ac resonant or something like that. Yes, this is my pitiful offering... a way to name it... Sheesh... When you're farther along and I have more time, I'll jump in, build it and offer my help... Jeff Parisse > I am not sure anyone realized that a > single turn primary could have a high > coupling like that! That is, of course, > key for this thing to work. Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Sun, 11 Aug 2002 10:47:14 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Sun, 11 Aug 2002 10:33:52 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: Re: OLTC update X-Mailing-List: archive/latest/744 X-Loop: tesla@pupman.com Original poster: "tesla by way of Terry Fritz " Great scheme to ensure current sharing Terry Thought FWIW Is it better to use more lower value caps to keep the ESR lower or are the 10 by 4.7uF caps a good compromise for ESR. Best Ted L in NZ Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Sun, 11 Aug 2002 10:47:07 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Sun, 11 Aug 2002 10:35:54 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: Re: OLTC update X-Mailing-List: archive/latest/748 X-Loop: tesla@pupman.com Original poster: "Phil@TCBFW by way of Terry Fritz " Terry, Hat's off to you for the idea on current sharing . . . I've used this idea before in a non-TC application (my load to each IGBT was inductive not capacitive) and it worked great until trying to get the IGBT's to switch in the nano second range. You should be able to compensate for this by sending the trigger pulse to each IGBT through a PFN, do a bit of low power adjusting and I think you'll have "TC The Next Generation" Waiting with anticipation to see your results !!! Phil TCBFW ----- Original Message ----- From: "Tesla list" To: Cc: "David Sharpe" Sent: Saturday, August 10, 2002 10:43 PM Subject: OLTC update > Original poster: "Terry Fritz" > > Hi All, > > To update the IGBT current sharing in the OLTC... > > http://hot-streamer.com/temp/OLTC8-10-02.gif > > Yep! We have ten independent primary caps too. If we hook them up like > this, the cap's impedance naturally hard balances the current to the IGBTs. > It is just a done deal, "painfully" simple... nothing can go wrong. It's > gotta work. Even if just one IGBT turns on I "think" it self protects... > If one stays out, it self protects... (the frequency is wrong, but who > cares...) > > This solution to current sharing of the OLTC's IGBTs is so beautiful, it > makes me wanna cry... > > Cheers, > > Terry > > > Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Sun, 11 Aug 2002 10:54:56 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Sun, 11 Aug 2002 10:51:40 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: Re: OLTC update X-Mailing-List: archive/latest/753 X-Loop: tesla@pupman.com Original poster: "Terry Fritz" Hi Ted, The 4.7uF 600V caps are the largest in the right range that they make. They just hapened to turn out matching up to the IGBTs well. It just sort of worked out just right ;-) Cheers, Terry At 10:11 PM 8/11/2002 +1200, you wrote: >Great scheme to ensure current sharing Terry >Thought FWIW >Is it better to use more lower value caps to keep the ESR lower or are the >10 by 4.7uF caps a good compromise for ESR. >Best >Ted L in NZ > Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Sun, 11 Aug 2002 13:12:50 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Sun, 11 Aug 2002 13:05:44 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: Re: OLTC update X-Mailing-List: archive/latest/760 X-Loop: tesla@pupman.com Original poster: "Paul Nicholson by way of Terry Fritz " I guess the main difficulty with the OLTC is that a large primary cap is required in order to get a decent firing energy. Thus an impractically small primary inductance is called for. Barry wrote: > Would it be easier to build a secondary that couples to a > higher harmonic of the primary? Hmm. Putting the energy into a primary (or any coil) by connecting a charged cap across its ends tends to excite the coil at its lowest resonant mode, which is what we'd call its Fres. Only a little of the firing energy goes into higher modes of the primary. To excite the primary at a higher mode (not a harmonic), one way would be to simultaneously discharge several caps, strategically placed along the winding, alternated with ground connections. The initial firing energy would be shared across all the caps. This would seem to be feasible given the use of semiconductor switches. Apart from the difficulty with tuning, so far so good. The problem then is to couple effectively to the secondary. Now with the primary at a higher mode, current in parts of the primary will tend to be pulling against current in other parts of the primary as far as the inductive coupling to the secondary quarter wave is concerned. And as the mode number gets higher, the overall cancellation of the field from the primary becomes more complete. Therefore, it would be necessary, in order to obtain a cooperative field from each half-wave current segment of the primary, to reverse the winding sense between each firing cap. But doing so would destroy the transmission line properties which were giving you the particular mode, and the system degenerates almost into a set of parallel primary windings, each with its own personal cap. So to persue Barry's rather interesting idea, I think it would be necessary to make sure that the secondary was closely coupled to only one half-wave's worth of the primary, and that the rest of the primary contributes relatively less to the coupling. Acmi can be used to model the coupling to a secondary from a primary which has caps placed along it's length, so long as these caps are large compared to the self-C of the primary itself, which it's safe to assume. Note that this might not be possible with traditional spark gaps because of the need for simultaneous switching. Apart from tuning, I think the other main problem with this approach would be how to ensure that large amounts of energy don't converge onto a single cap of the primary, which it's perfectly free to do so once the thing is released into resonance - given unpredictable reflections from the top of the secondary. We wouldn't want any of the caps to suddenly find itself carrying a whole lot more energy than it started out with. But then we do have scope for controlling the timing of the switching, so maybe things could be controlled automatically somehow. If you get into that sort of territory, you can conjecture building up a traveling pulse waveform along a primary, by firing caps consecutively, so that the energy is built up into a single broadband pulse. You'd set things for a steady impedance transformation along the way, and the primary would couple to or merge into a secondary, which would continue the impedance transformation (by some cunning choice of coil profile) to give a single huge voltage pulse at the top. Picture a deep atlantic wave approaching a beach, rolling up in the shallows, trading width for height. The deep sea wave sees a gradual impedance change as the beach applies some extra boundary conditions. Surfers know the beaches with the best profiles - wonder what shape of coil would turn a long duration, low-voltage, high-current, broadband pulse applied at one end, into a short, high voltage, low current pulse at the other. Note that this is quite unlike a normal TC. We're now firing up multiple resonant modes, and timing them so that they momentarily converge to a single giant voltage pulse at one end (preferably the far end) of the coil. But before anyone gets too excited, there are some problems with this approach and it's not likely to give you any more topvolts per joule than a regular TC, if my sums are correct. But, I think I like Barry's idea, because it opens up some interesting possibilities. Whether it would bo any better than, say, a normal primary with lots of separate caps and switches paralleled across it would have to be considered. All in all, I'm following this OLTC stuff with great interest. -- Paul Nicholson -- Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Sun, 11 Aug 2002 18:08:30 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Sun, 11 Aug 2002 17:52:42 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: Re: OLTC update X-Mailing-List: archive/latest/782 X-Loop: tesla@pupman.com Original poster: "tesla by way of Terry Fritz " Hi Terry/List The idea of tuning by selecting the Number of IGBT's operating seems great. You could possibly have "tuning " IGBTs which have much smaller caps which are selected just to tune the coil. Best Ted L in NZ PS thank you for sharing your work with us all ----- Original Message ----- From: "Tesla list" To: Sent: Monday, August 12, 2002 7:05 AM Subject: Re: OLTC update > Original poster: "Paul Nicholson by way of Terry Fritz " > > I guess the main difficulty with the OLTC is that a large primary > cap is required in order to get a decent firing energy. Thus an > impractically small primary inductance is called for. > > Barry wrote: > > > Would it be easier to build a secondary that couples to a > > higher harmonic of the primary? > > Hmm. Putting the energy into a primary (or any coil) by > connecting a charged cap across its ends tends to excite the coil > at its lowest resonant mode, which is what we'd call its Fres. > Only a little of the firing energy goes into higher modes > of the primary. > > To excite the primary at a higher mode (not a harmonic), one way > would be to simultaneously discharge several caps, strategically > placed along the winding, alternated with ground connections. > The initial firing energy would be shared across all the caps. > This would seem to be feasible given the use of semiconductor > switches. > > Apart from the difficulty with tuning, so far so good. > > The problem then is to couple effectively to the secondary. Now > with the primary at a higher mode, current in parts of the primary > will tend to be pulling against current in other parts of the > primary as far as the inductive coupling to the secondary > quarter wave is concerned. And as the mode number gets higher, > the overall cancellation of the field from the primary becomes > more complete. > > Therefore, it would be necessary, in order to obtain a cooperative > field from each half-wave current segment of the primary, to > reverse the winding sense between each firing cap. But doing so > would destroy the transmission line properties which were giving > you the particular mode, and the system degenerates almost into > a set of parallel primary windings, each with its own personal cap. > > So to persue Barry's rather interesting idea, I think it would be > necessary to make sure that the secondary was closely coupled to > only one half-wave's worth of the primary, and that the rest of > the primary contributes relatively less to the coupling. Acmi > can be used to model the coupling to a secondary from a primary > which has caps placed along it's length, so long as these caps are > large compared to the self-C of the primary itself, which it's > safe to assume. > > Note that this might not be possible with traditional spark gaps > because of the need for simultaneous switching. > > Apart from tuning, I think the other main problem with this > approach would be how to ensure that large amounts of energy don't > converge onto a single cap of the primary, which it's perfectly > free to do so once the thing is released into resonance - given > unpredictable reflections from the top of the secondary. We > wouldn't want any of the caps to suddenly find itself carrying > a whole lot more energy than it started out with. > > But then we do have scope for controlling the timing of the > switching, so maybe things could be controlled automatically > somehow. If you get into that sort of territory, you can > conjecture building up a traveling pulse waveform along a primary, > by firing caps consecutively, so that the energy is built up > into a single broadband pulse. You'd set things for a steady > impedance transformation along the way, and the primary would > couple to or merge into a secondary, which would continue the > impedance transformation (by some cunning choice of coil profile) > to give a single huge voltage pulse at the top. Picture a deep > atlantic wave approaching a beach, rolling up in the shallows, > trading width for height. The deep sea wave sees a gradual > impedance change as the beach applies some extra boundary > conditions. Surfers know the beaches with the best profiles - > wonder what shape of coil would turn a long duration, low-voltage, > high-current, broadband pulse applied at one end, into a short, > high voltage, low current pulse at the other. Note that this is > quite unlike a normal TC. We're now firing up multiple resonant > modes, and timing them so that they momentarily converge to a > single giant voltage pulse at one end (preferably the far end) > of the coil. But before anyone gets too excited, there are some > problems with this approach and it's not likely to give you any > more topvolts per joule than a regular TC, if my sums are correct. > > But, I think I like Barry's idea, because it opens up some > interesting possibilities. Whether it would bo any better than, > say, a normal primary with lots of separate caps and switches > paralleled across it would have to be considered. All in all, > I'm following this OLTC stuff with great interest. > -- > Paul Nicholson > -- > > > > Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Sun, 11 Aug 2002 21:47:41 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Sun, 11 Aug 2002 21:33:46 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: Re: OLTC update X-Mailing-List: archive/latest/798 X-Loop: tesla@pupman.com Original poster: "Antonio Carlos M. de Queiroz by way of Terry Fritz " Tesla list wrote: > Original poster: "Paul Nicholson by way of Terry Fritz " > But then we do have scope for controlling the timing of the > switching, so maybe things could be controlled automatically > somehow. If you get into that sort of territory, you can > conjecture building up a traveling pulse waveform along a primary, > by firing caps consecutively, so that the energy is built up > into a single broadband pulse. You'd set things for a steady > impedance transformation along the way, and the primary would > couple to or merge into a secondary, which would continue the > impedance transformation (by some cunning choice of coil profile) > to give a single huge voltage pulse at the top. Picture a deep > atlantic wave approaching a beach, rolling up in the shallows, > trading width for height. The deep sea wave sees a gradual > impedance change as the beach applies some extra boundary > conditions. Surfers know the beaches with the best profiles - > wonder what shape of coil would turn a long duration, low-voltage, > high-current, broadband pulse applied at one end, into a short, > high voltage, low current pulse at the other. Note that this is > quite unlike a normal TC. We're now firing up multiple resonant > modes, and timing them so that they momentarily converge to a > single giant voltage pulse at one end (preferably the far end) > of the coil. But before anyone gets too excited, there are some > problems with this approach and it's not likely to give you any > more topvolts per joule than a regular TC, if my sums are correct. This is precisely a "multiple resonance network". See the references at: http://www.coe.ufrj.br/~acmq/tesla/magnifier.html A system with many stages looks as a kind of nonuniform transmission line, where the pulse caused by a capacitor discharge at the input evolves to a high-voltage pulse at the output. The directly coupled system that I recently described is the simplest version, that behaves as a Tesla coil. The next one behaves as a magnifier, and the same idea can be extended to any number of sections, with higher and higher gain as stages are added and more reflections are allowed (higher modes of operation, or less frequency spread in the resonances). I have a program that can design and simulate these circuits, up to 12 or 13 resonances, at: ftp://coe.ufrj.br/pub/acmq/mres.zip Antonio Carlos M. de Queiroz Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Sun, 11 Aug 2002 21:42:44 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Sun, 11 Aug 2002 21:37:02 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: Re: OLTC update X-Mailing-List: archive/latest/804 X-Loop: tesla@pupman.com Original poster: "D.C. Cox by way of Terry Fritz " You might also consider an extra large ferrite core in only the first 4-6 in of the sec. coil. Ferrite would only be perhaps 20% of sec. coil dia. This would help drop opr. freq perhaps into the range of your primary system so a nice primary load of perhaps 20-30 turns could occur. I'm far from being a solid state engr. so this is only a suggestion for consideration of those actively working on this device. Best regards, Dr. Resonance ----- Original Message ----- From: "Tesla list" To: Sent: Sunday, August 11, 2002 4:52 PM Subject: Re: OLTC update > Original poster: "tesla by way of Terry Fritz " > > Hi Terry/List > The idea of tuning by selecting the Number of IGBT's operating seems great. > You could possibly have "tuning " IGBTs which have much smaller caps which > are selected just to tune the coil. > Best > Ted L in NZ > PS thank you for sharing your work with us all > ----- Original Message ----- > From: "Tesla list" > To: > Sent: Monday, August 12, 2002 7:05 AM > Subject: Re: OLTC update > > > > Original poster: "Paul Nicholson by way of Terry Fritz > " > > > > I guess the main difficulty with the OLTC is that a large primary > > cap is required in order to get a decent firing energy. Thus an > > impractically small primary inductance is called for. > > > > Barry wrote: > > > > > Would it be easier to build a secondary that couples to a > > > higher harmonic of the primary? > > > > Hmm. Putting the energy into a primary (or any coil) by > > connecting a charged cap across its ends tends to excite the coil > > at its lowest resonant mode, which is what we'd call its Fres. > > Only a little of the firing energy goes into higher modes > > of the primary. > > > > To excite the primary at a higher mode (not a harmonic), one way > > would be to simultaneously discharge several caps, strategically > > placed along the winding, alternated with ground connections. > > The initial firing energy would be shared across all the caps. > > This would seem to be feasible given the use of semiconductor > > switches. > > > > Apart from the difficulty with tuning, so far so good. > > > > The problem then is to couple effectively to the secondary. Now > > with the primary at a higher mode, current in parts of the primary > > will tend to be pulling against current in other parts of the > > primary as far as the inductive coupling to the secondary > > quarter wave is concerned. And as the mode number gets higher, > > the overall cancellation of the field from the primary becomes > > more complete. > > > > Therefore, it would be necessary, in order to obtain a cooperative > > field from each half-wave current segment of the primary, to > > reverse the winding sense between each firing cap. But doing so > > would destroy the transmission line properties which were giving > > you the particular mode, and the system degenerates almost into > > a set of parallel primary windings, each with its own personal cap. > > > > So to persue Barry's rather interesting idea, I think it would be > > necessary to make sure that the secondary was closely coupled to > > only one half-wave's worth of the primary, and that the rest of > > the primary contributes relatively less to the coupling. Acmi > > can be used to model the coupling to a secondary from a primary > > which has caps placed along it's length, so long as these caps are > > large compared to the self-C of the primary itself, which it's > > safe to assume. > > > > Note that this might not be possible with traditional spark gaps > > because of the need for simultaneous switching. > > > > Apart from tuning, I think the other main problem with this > > approach would be how to ensure that large amounts of energy don't > > converge onto a single cap of the primary, which it's perfectly > > free to do so once the thing is released into resonance - given > > unpredictable reflections from the top of the secondary. We > > wouldn't want any of the caps to suddenly find itself carrying > > a whole lot more energy than it started out with. > > > > But then we do have scope for controlling the timing of the > > switching, so maybe things could be controlled automatically > > somehow. If you get into that sort of territory, you can > > conjecture building up a traveling pulse waveform along a primary, > > by firing caps consecutively, so that the energy is built up > > into a single broadband pulse. You'd set things for a steady > > impedance transformation along the way, and the primary would > > couple to or merge into a secondary, which would continue the > > impedance transformation (by some cunning choice of coil profile) > > to give a single huge voltage pulse at the top. Picture a deep > > atlantic wave approaching a beach, rolling up in the shallows, > > trading width for height. The deep sea wave sees a gradual > > impedance change as the beach applies some extra boundary > > conditions. Surfers know the beaches with the best profiles - > > wonder what shape of coil would turn a long duration, low-voltage, > > high-current, broadband pulse applied at one end, into a short, > > high voltage, low current pulse at the other. Note that this is > > quite unlike a normal TC. We're now firing up multiple resonant > > modes, and timing them so that they momentarily converge to a > > single giant voltage pulse at one end (preferably the far end) > > of the coil. But before anyone gets too excited, there are some > > problems with this approach and it's not likely to give you any > > more topvolts per joule than a regular TC, if my sums are correct. > > > > But, I think I like Barry's idea, because it opens up some > > interesting possibilities. Whether it would bo any better than, > > say, a normal primary with lots of separate caps and switches > > paralleled across it would have to be considered. All in all, > > I'm following this OLTC stuff with great interest. > > -- > > Paul Nicholson > > -- > > > > > > > > > > Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Sun, 11 Aug 2002 22:52:56 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Sun, 11 Aug 2002 22:48:01 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: OLTC update X-Mailing-List: archive/latest/807 X-Loop: tesla@pupman.com Original poster: "Terry Fritz" Hi All, Today I worked on the control box that controls the IGBT array: http://hot-streamer.com/temp/OLTC-PowerContFront.jpg http://hot-streamer.com/temp/OLTC-PowerContBack.jpg http://hot-streamer.com/temp/OLTC-PowerContIn.jpg It still needs the current transformer and LM311 circuit, but I tested the LMC555 timer part. http://hot-streamer.com/temp/OLTC8-11-01.gif The schematic is at: http://hot-streamer.com/temp/OLTC-TimingControl.gif I changed the 50K pot to a 100K 10 turn pot and put a counting dial on it. I also put a 100nF cap in series with the 10nF cap to get 9.90nF. Since the pulse width = 1.1RC, this makes the dial count off directly in uS. So it is very easy to just set the dwell time with this dial. I hope it won't be needed other than for testing. The pot and dial run about $40! I was very surprised at how accurate the dial was! Dial setting Pulse width(uS) 40 39.81 50 49.67 60 59.55 70 69.54 80 79.52 90 89.49 100 99.99 120 119.8 130 129.8 140 139.8 150 149.4 200 200.1 400 401.5 600 603.0 800 802.6 1000 999.4 It weighs in at 1 lb. 5 Oz. mostly the heavy aluminum box that should protect it a bit from streamers. Mostly waiting for parts to come tomorrow... Cheers, Terry Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Mon, 12 Aug 2002 18:28:44 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Mon, 12 Aug 2002 18:08:10 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: Re: OLTC update X-Mailing-List: archive/latest/858 X-Loop: tesla@pupman.com Original poster: "tesla by way of Terry Fritz " Hi Terry et al I know you probably need less time on EMAIL's and more on the OLTC but a thought to put in the mix follows. Presumably once you've got the OLTC running at 120bps firing on mains peaks the design would be ammenable to firing at higher BPS to achieve more power thruput. Firing at other times as close to pks as the charging time constant and current carrying capacities of the components being the limiting factors Rgds Ted L in NZ Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Tue, 13 Aug 2002 01:19:20 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Tue, 13 Aug 2002 01:16:51 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: OLTC update X-Mailing-List: archive/latest/885 X-Loop: tesla@pupman.com Original poster: "Terry Fritz" Hi All, I got the IGBT timing controller done tonight. Here are the four side pictures. Sorry they are about 400k each but I wanted to keep the details... http://hot-streamer.com/temp/OLTCigbtC-8-12-01.jpg http://hot-streamer.com/temp/OLTCigbtC-8-12-02.jpg http://hot-streamer.com/temp/OLTCigbtC-8-12-03.jpg http://hot-streamer.com/temp/OLTCigbtC-8-12-04.jpg Here is the schematic: http://hot-streamer.com/temp/OLTCigbtC-8-12-05.gif I tested it with the HP 33120a function generator programmed with this test waveform: http://hot-streamer.com/temp/OLTCigbtC-8-12-06.gif It is like the charging waveform and has uneven bottom spikes and noise in parts of the signal. I used my low-Z amp, Pearson 411 current probe, and scope to test the controller by feeding this current waveform into it: http://hot-streamer.com/temp/OLTCigbtC-8-12-08.gif The controller tracks very well and handles the uneven spikes. The noise causes misfiring. Something to be careful of on the coil but I think it will be ok. http://hot-streamer.com/temp/OLTCigbtC-8-12-07.gif Here is a close up of the 8 volt firing signal (top) and the input current (bottom). Nice and clean. The real current waveform will actually be considerably sharper. Cheers, Terry Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Tue, 13 Aug 2002 23:55:27 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Tue, 13 Aug 2002 23:41:07 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: OLTC update X-Mailing-List: archive/latest/976 X-Loop: tesla@pupman.com Original poster: "Terry Fritz" Hi All, Today I made a fairly accurate MicroSim Model of the OLTC: http://hot-streamer.com/temp/OLTCigbtC-8-13-01.gif http://hot-streamer.com/temp/OLTCigbtC-8-13-02.gif I change a few component values in the controller between the LM311 and the LMC555 for better control: http://hot-streamer.com/temp/OLTCigbtC-8-13-03.gif Cheers, Terry Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Wed, 14 Aug 2002 08:45:07 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Wed, 14 Aug 2002 08:38:21 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: RE: OLTC update X-Mailing-List: archive/latest/995 X-Loop: tesla@pupman.com Original poster: "Lau, Gary by way of Terry Fritz " Hi Terry: I noticed that contrary to the practice with spark gap coils, you are placing the power supply across the tank cap, rather than the "gap". This places a more difficult burden on the filter network between the tank and the power supply, to keep the RF out of your mains. Have you examined the signals going back to the mains? I see the obvious problem with placing the power supply across the gap - a turn-on fault will short out the power supply and smoke will flow... Maybe a lower current IGBT could be placed in series with the PS, breaking the connection whenever the main gap IGBT's are told to turn on? Also, with the distributed tank cap/IGBT concept, I assume you plan to have a separate decoupling network/filter for each segment? Regards, Gary Original poster: "Terry Fritz" Hi All, Today I made a fairly accurate MicroSim Model of the OLTC: http://hot-streamer.com/temp/OLTCigbtC-8-13-01.gif http://hot-streamer.com/temp/OLTCigbtC-8-13-02.gif I change a few component values in the controller between the LM311 and the LMC555 for better control: http://hot-streamer.com/temp/OLTCigbtC-8-13-03.gif Cheers, Terry Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Wed, 14 Aug 2002 11:44:35 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Wed, 14 Aug 2002 11:39:02 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: Re: OLTC update X-Mailing-List: archive/latest/1001 X-Loop: tesla@pupman.com Original poster: "Jim Lux by way of Terry Fritz " Jumping in ahead of Terry here... In the typical TC where you're feeding the tank with a high impedance AC source (i.e. a NST ), then you put the gap across the transformer to serve as a safety gap, with the primary C charging through the primary L, and the voltage source shorting during the spark. Fortunately, the source is current limited (by design), and the spark doesn't last very long (low DC), and you don't really want to start trying to recharge the C during the "bang" anyway. In Terry's design, it's more of a resonant charger from a DC source, so you need to have the primary C fed through an inductor from a fairly stiff (low impedance) source. Tesla list wrote: > > Original poster: "Lau, Gary by way of Terry Fritz " > > Hi Terry: > > I noticed that contrary to the practice with spark gap coils, you are > placing the power supply across the tank cap, rather than the "gap". This > places a more difficult burden on the filter network between the tank and > the power supply, to keep the RF out of your mains. Have you examined the > signals going back to the mains? I see the obvious problem with placing > the power supply across the gap - a turn-on fault will short out the power > supply and smoke will flow... Maybe a lower current IGBT could be placed > in series with the PS, breaking the connection whenever the main gap IGBT's > are told to turn on? > > Also, with the distributed tank cap/IGBT concept, I assume you plan to have > a separate decoupling network/filter for each segment? > > Regards, Gary > > Original poster: "Terry Fritz" > > Hi All, > > Today I made a fairly accurate MicroSim Model of the OLTC: > http://hot-streamer.com/temp/OLTCigbtC-8-13-01.gif > http://hot-streamer.com/temp/OLTCigbtC-8-13-02.gif > I change a few component values in the controller between the LM311 and the > LMC555 for better control: > http://hot-streamer.com/temp/OLTCigbtC-8-13-03.gif > > Cheers, > > Terry Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Wed, 14 Aug 2002 11:56:15 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Wed, 14 Aug 2002 11:52:11 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: RE: OLTC update X-Mailing-List: archive/latest/1004 X-Loop: tesla@pupman.com Original poster: "Terry Fritz" HI Gary At 08:48 AM 8/14/2002 -0400, "Lau, Gary" wrote: >Hi Terry: > >I noticed that contrary to the practice with spark gap coils, you are >placing the power supply across the tank cap, rather than the "gap". This >places a more difficult burden on the filter network between the tank and >the power supply, to keep the RF out of your mains. Have you examined the >signals going back to the mains? I see the obvious problem with placing the >power supply across the gap - a turn-on fault will short out the power >supply and smoke will flow... Maybe a lower current IGBT could be placed in >series with the PS, breaking the connection whenever the main gap IGBT's are >told to turn on? Since I quench the coil fairly soon and the 75mH inductors and caps are such powerful filters anyway, it really does not matter at all. If you go across the caps, or across the opened gap, it's all pretty much the same. Of course, the "noise" problems are far far less in this case anyway. > >Also, with the distributed tank cap/IGBT concept, I assume you plan to have >a separate decoupling network/filter for each segment? Since the primary system impedance is very low, it probably only takes like a 1 ohm resistor to "isolate" each cap. Need to look into this today. ======== From: "Daniel Hess" > >Terry; > >OLTC ??? > >Daniel Off-Line Tesla Coil See: http://hot-streamer.com/OLTC/ =============== Cheers, Terry Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Fri, 16 Aug 2002 23:36:57 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Fri, 16 Aug 2002 23:30:56 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: OLTC update X-Mailing-List: archive/latest/1152 X-Loop: tesla@pupman.com Original poster: "Terry Fritz" Hi All, Wow! Long day today :-)) Mostly spent figuring out the inductor... Here is a picture of the parts so far: http://hot-streamer.com/temp/OLTC08-16-09.jpg The only parts of the coil that are not there, are the SonoTube secondary form and the top load. All the primary control and parts are there! Not much to it... The control box weighs 9 pounds but about 5 pounds of that is in the orange wire. Everything on the Lexan base weighs 16 pounds. The Lexan itself is the heaviest part aside from the inductor. I think the secondary and top load will come in at 15 pounds. So the total system weight is 40 pounds, or 10 pounds less than a 15/60 NST ;-) Cheers, Terry Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Sat, 17 Aug 2002 10:58:01 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Sat, 17 Aug 2002 10:45:22 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: Re: OLTC update X-Mailing-List: archive/latest/1159 X-Loop: tesla@pupman.com Original poster: "Brian by way of Terry Fritz " Geeze, your gonna need a 20 lb. block of lead to keep it from tipping over in the wind! Awesome! cul brian f. ----- Original Message ----- From: "Tesla list" To: Sent: Saturday, August 17, 2002 1:30 AM Subject: OLTC update > Original poster: "Terry Fritz" > > Hi All, > > Wow! Long day today :-)) > > Mostly spent figuring out the inductor... > > Here is a picture of the parts so far: > > http://hot-streamer.com/temp/OLTC08-16-09.jpg > > The only parts of the coil that are not there, are the SonoTube secondary > form and the top load. > > All the primary control and parts are there! Not much to it... > > The control box weighs 9 pounds but about 5 pounds of that is in the orange > wire. > > Everything on the Lexan base weighs 16 pounds. The Lexan itself is the > heaviest part aside from the inductor. > > I think the secondary and top load will come in at 15 pounds. > > So the total system weight is 40 pounds, or 10 pounds less than a 15/60 NST > ;-) > > Cheers, > > Terry > > > Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Sun, 18 Aug 2002 00:36:19 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Sun, 18 Aug 2002 00:32:13 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: OLTC update X-Mailing-List: archive/latest/1219 X-Loop: tesla@pupman.com Original poster: "Terry Fritz" Hi All, I got the caps and IGBTs mounted up: http://hot-streamer.com/temp/OLTC08-17-01.jpg http://hot-streamer.com/temp/OLTC08-17-02.jpg Doesn't look like much does it ;-) But right there you have your primary coil, MMC, and solid state spark gap... Only 9 pounds... Each of those ten IGBTs can pump 200 amps peak and the caps max out at 500 amps each :-)))) The caps can do 168 amps RMS and the IGBTs 510 amps DC all day long ;-)) One heck of a lot of current there!! We may not have 20,00 volts, but we got current ;-)) I figure if I have a primary that can couple to the secondary at a K of 0.15 and sustain a ringdown of 2000+ amps... I can make a Tesla coil :-))) Sort of an MMC and solid state spark gap all wrapped up in one ;-)) Went together pretty easily, but I have lots of tricks ;-)) Soldering IGBT leads to 0.025 copper plate takes a big soldering iron on the "ludicrous" setting (I used two ;-)). Took about 1/2 second of "heat" ;-)) It would almost power on enough to test the Fo frequency, but I ran out of steam tonight. I am going to order some torroid inductors cores from this cool place Jim mentioned: http://www.alphacore.com/stcores.htm Nice big cores at very good prices. If this OLTC thing is a "go", this would be a great place to get the inductor. Might also be good for MOT folks for a current limiting inductor. Mostly spent time doing yardwork and paperwork today... Cheers, Terry Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Sun, 18 Aug 2002 13:28:57 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Sun, 18 Aug 2002 13:25:07 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: Re: OLTC update X-Mailing-List: archive/latest/1247 X-Loop: tesla@pupman.com Original poster: "Finn Hammer by way of Terry Fritz " Soldering IGBT > leads to 0.025 copper plate takes a big soldering iron on the "ludicrous" > setting (I used two ;-)). Took about 1/2 second of "heat" ;-)) > > Cheers, > > Terry Hi Terry! Next time, you should try to slot the copper plate like this: http://www.wimshurst.com/ledninger.jpg It shows 4 runs of RG 219 (you know, the antenna stuff, debraided) soldered to 0.1" copper plate. Cheers, Finn Hammer Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Sun, 18 Aug 2002 20:04:31 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Sun, 18 Aug 2002 19:53:31 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: Re: OLTC update X-Mailing-List: archive/latest/1259 X-Loop: tesla@pupman.com Original poster: "by way of Terry Fritz " > > Original poster: "Terry Fritz" > > Hi All, > > I got the caps and IGBTs mounted up: > > http://hot-streamer.com/temp/OLTC08-17-01.jpg > > http://hot-streamer.com/temp/OLTC08-17-02.jpg It looks as all three primary coils are in use, are they? --------------------------------------- Jonathon Reinhart hot-streamer.com/jonathon Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Sun, 18 Aug 2002 20:58:34 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Sun, 18 Aug 2002 20:50:58 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: OLTC Update X-Mailing-List: archive/latest/1267 X-Loop: tesla@pupman.com Original poster: "Terry Fritz" Hi All, I got the OLTC's primary circuit running off low voltage DC supplies tonight. http://hot-streamer.com/temp/OLTC08-18-01.jpg http://hot-streamer.com/temp/OLTC08-18-02.jpg Hard to find the thing under all the leads and test equipment... Here are some close ups of the good parts: http://hot-streamer.com/temp/OLTC08-18-03.jpg http://hot-streamer.com/temp/OLTC08-18-04.jpg It will look much simpler when cleaned up ;-)) So no more of those goofy MicroSim charts... Here is a real waveform from the primary: http://hot-streamer.com/temp/OLTC08-18-05.gif I was able to do a very important stability test where the IGBT controller circuits were actually all running but with a bad input waveform. This checks to see if the coil would do anything "bad" if the control electronics go nuts: http://hot-streamer.com/temp/OLTC08-18-06.gif No problem at all :-)) Here is the primary voltage and drive signal at about 50 volts input (all I can reasonably do right now): http://hot-streamer.com/temp/OLTC08-18-07.gif I will have to figure out the loss and divide it by ten for the 500 volt case where the coil will actually run. The losses of IGBTs or more or less proportional to current, but the power is proportional to current squared. So as you increase the current (drive voltage), efficiency of the coil increases. So right now, the all important primary loss looks fine. There is one odd thing. The coil's Fo frequency seems to be 38kHz. That is higher than I was thinking by about 6kHz. I will have to check to be sure all the IGBTs are coming on, but it may just be due to the difficulties in measuring (and guessing) sub micro-henry inductances. When you dealing with 500nH inductors, you just never know how they are going to turn out ;-)) Higher frequency is very nice since it reduces the size of the secondary. However, current increases too and I am a bit concerned about that. In any case, it looks like we have some room to play :-)) The diagram of the IGBTS, caps, and control stuff is here (sorry about the very rough sketch ;-)) http://hot-streamer.com/temp/OLTC08-18-09.gif Don't let this seem too complicated. Barely 10$ worth of odd parts there and you could hold them all in your hand. If you take out the resistors and divide the basic circuit by ten. It only has two "important" parts. The IGBT and the primary cap. Here is something fun! Ever try to quench a gap with all the power still in the primary ;-)) http://hot-streamer.com/temp/OLTC08-18-08.gif No doubt about it. Even though the anti-parallel diodes are still in circuit, Turning off the IGBTs stops the whole show right quick! The trailing "screeeeem!" is the primary wondering where to dump the energy. I have no idea where it goes... Probably would not want to do that at full power without a secondary :-)) Oh! It's noisy!! Forget that "silent" thing!" The caps squeal like pigs! I have not figured out the current yet, but the low frequency and high current vibrates the caps like little speakers. It sounds like, and is about as loud, as a florescent light ballast that has gone bad. I wonder if mechanical vibration of the caps is a problem... Probably no big deal but I guess solid state coil's that depend on high currents or going to have noisy caps. I was only running at 1/10 voltage tonight. I imagine it gets really loud at 550 VDC =:O I could kick myself for one thing... I have no way of getting a current monitor in the primary circuit :-(( I have like six Pearson current monitors here (one is a 50,000 amp!) and no way to insert one in the circuit. I guest that is why they make the split clamp one types too (and charge 5X for them! They know when they gotcha!) So I decided to stop and think at this point tonight rather than keep fiddling with it till I blow it up :-)) But all seems to be going fine. Cheers, Terry Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Sun, 18 Aug 2002 23:19:50 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Sun, 18 Aug 2002 23:09:46 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: Re: OLTC Update X-Mailing-List: archive/latest/1279 X-Loop: tesla@pupman.com Original poster: "Eddie Burwell by way of Terry Fritz " At 08:50 PM 8/18/02 -0600, you wrote: >Original poster: "Terry Fritz" >I could kick myself for one thing... I have no way of getting a current >monitor in the primary circuit :-(( I have like six Pearson current >monitors here (one is a 50,000 amp!) and no way to insert one in the >circuit. I guest that is why they make the split clamp one types too (and >charge 5X for them! They know when they gotcha!) > Perhaps you could wind a Rogowski coil around a piece of hose or something similar. Use your favorite opamp to make an integrator. You could calibrate it against one of your Pearson transformers. some links that turned up on google: http://homepage.ntlworld.com/rocoil/Pr9.pdf http://www.rocoil.cwc.net/ Eddie Burwell Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Mon, 19 Aug 2002 08:36:51 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Mon, 19 Aug 2002 08:13:55 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: RE: OLTC Update X-Mailing-List: archive/latest/1282 X-Loop: tesla@pupman.com Original poster: "by way of Terry Fritz " Hi Terry, > -----Original Message----- > From: tesla@pupman.com [mailto:tesla@pupman.com] > Sent: 19. elokuuta 2002 05:51 > To: tesla@pupman.com > Subject: OLTC Update > > > Original poster: "Terry Fritz" > The diagram of the IGBTS, caps, and control stuff is here > (sorry about the > very rough sketch ;-)) > > http://hot-streamer.com/temp/OLTC08-18-09.gif > I know you'll soon get bored from all the suggestions you are getting from all around the world, but here is one more :) Make the life of your IGBT easier by lowering their drive voltage to, say, 15V and the TVS voltage to 16V. A 20V TVS easily has a clamping voltage of well over 25V. More, the IGBTs conduct already with about 12V. Leave them more margin and they'll stay with you a longer time, hopefully :) Best Regards Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Mon, 19 Aug 2002 08:36:52 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Mon, 19 Aug 2002 08:18:10 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: Re: OLTC Update X-Mailing-List: archive/latest/1284 X-Loop: tesla@pupman.com Original poster: "Bert Hickman by way of Terry Fritz " Terry, Congratulations - the system is really beginning to look good! Regarding current monitoring - how about monitoring current through just one of the tank capacitor leads via a smaller current transformer - should be the same (just smaller) as the total primary current. It'll be interesting to see how the system behaves with a secondary in place and how much quenching flexibility you've actually got. You should be able to quench at every other current zero crossing (limited by the HexFRED diodes). However, this is great, since you should be able to tweak the coupling so that there is always an even number of "half cycles" to complete secondary ringup. This implies that you may be able to hit "magical" coupling coefficients that are not easily achieved in disruptive systems - 0.28 or even 0.60(!) assuming the geometries permit. As previously mentioned, a possible downside is that, through transformer action, some of the secondary's energy will be extracted during secondary ringdown, resulting in partial recharging of the tank caps through the internal HexFRED diodes. But even this shouldn't be too much of a problem since the tank caps will only recharge when the induced tank EMF is greater than the voltage stored on the tank caps. Since the induced primary voltage will be constrained by the secondary-to-primary turns ratio (i.e., with the diode in the circuit energy transfer is no longer resonant between secondary and primary), the actual amount of power lost in this fashion should be comparatively small. And, unlike a spark gap, the energy is not actually lost, but is "recycled" back to the tank cap instead of being burned up. Great job, Terry - dang, you're getting me excited now...! Best regards, -- Bert -- -- Bert Hickman Stoneridge Engineering "Electromagically" Shrunken Coins! http://www.teslamania.com Tesla list wrote: > > Original poster: "Terry Fritz" > > Hi All, > > I got the OLTC's primary circuit running off low voltage DC supplies tonight. > > http://hot-streamer.com/temp/OLTC08-18-01.jpg > > http://hot-streamer.com/temp/OLTC08-18-02.jpg > > Hard to find the thing under all the leads and test equipment... Here are > some close ups of the good parts: > > http://hot-streamer.com/temp/OLTC08-18-03.jpg > > http://hot-streamer.com/temp/OLTC08-18-04.jpg > > It will look much simpler when cleaned up ;-)) > > So no more of those goofy MicroSim charts... Here is a real waveform from > the primary: > > http://hot-streamer.com/temp/OLTC08-18-05.gif > > I was able to do a very important stability test where the IGBT controller > circuits were actually all running but with a bad input waveform. This > checks to see if the coil would do anything "bad" if the control > electronics go nuts: > > http://hot-streamer.com/temp/OLTC08-18-06.gif > > No problem at all :-)) > > Here is the primary voltage and drive signal at about 50 volts input (all I > can reasonably do right now): > > http://hot-streamer.com/temp/OLTC08-18-07.gif > > I will have to figure out the loss and divide it by ten for the 500 volt > case where the coil will actually run. The losses of IGBTs or more or less > proportional to current, but the power is proportional to current squared. > So as you increase the current (drive voltage), efficiency of the coil > increases. So right now, the all important primary loss looks fine. > > There is one odd thing. The coil's Fo frequency seems to be 38kHz. That > is higher than I was thinking by about 6kHz. I will have to check to be > sure all the IGBTs are coming on, but it may just be due to the > difficulties in measuring (and guessing) sub micro-henry inductances. When > you dealing with 500nH inductors, you just never know how they are going to > turn out ;-)) Higher frequency is very nice since it reduces the size of > the secondary. However, current increases too and I am a bit concerned > about that. In any case, it looks like we have some room to play :-)) > > The diagram of the IGBTS, caps, and control stuff is here (sorry about the > very rough sketch ;-)) > > http://hot-streamer.com/temp/OLTC08-18-09.gif > > Don't let this seem too complicated. Barely 10$ worth of odd parts there > and you could hold them all in your hand. If you take out the resistors > and divide the basic circuit by ten. It only has two "important" parts. > The IGBT and the primary cap. > > Here is something fun! Ever try to quench a gap with all the power still > in the primary ;-)) > > http://hot-streamer.com/temp/OLTC08-18-08.gif > > No doubt about it. Even though the anti-parallel diodes are still in > circuit, Turning off the IGBTs stops the whole show right quick! The > trailing "screeeeem!" is the primary wondering where to dump the energy. I > have no idea where it goes... Probably would not want to do that at full > power without a secondary :-)) > > Oh! It's noisy!! Forget that "silent" thing!" The caps squeal like pigs! > I have not figured out the current yet, but the low frequency and high > current vibrates the caps like little speakers. It sounds like, and is > about as loud, as a florescent light ballast that has gone bad. I wonder > if mechanical vibration of the caps is a problem... Probably no big deal > but I guess solid state coil's that depend on high currents or going to > have noisy caps. I was only running at 1/10 voltage tonight. I imagine it > gets really loud at 550 VDC =:O > > I could kick myself for one thing... I have no way of getting a current > monitor in the primary circuit :-(( I have like six Pearson current > monitors here (one is a 50,000 amp!) and no way to insert one in the > circuit. I guest that is why they make the split clamp one types too (and > charge 5X for them! They know when they gotcha!) > > So I decided to stop and think at this point tonight rather than keep > fiddling with it till I blow it up :-)) But all seems to be going fine. > > Cheers, > > Terry > > Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Mon, 19 Aug 2002 12:49:38 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Mon, 19 Aug 2002 12:45:23 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: Re: OLTC Update X-Mailing-List: archive/latest/1300 X-Loop: tesla@pupman.com Original poster: "Terry Fritz" Hi Eddie, I guess I really don't need to measure the current for any great reason. The physics of the thing really defines what it "has" to be. My only concern was to verify the IGBT current sharing and that of the three loops. I just punted and borrowed a probe to check the IGBT current sharing (buried in the bottom of my desk at work...). The current sharing is perfect. ;-)) I think I can find a big clamp probe for the loops too this afternoon. So not a big deal really, once the currents are verified, it is just a done deal. One nice thing about these coils is that the voltages are low enough that just any standard scope type scope probes work on it. That really really helps things ;-)) Cheers, Terry At 12:41 AM 8/19/2002 -0600, you wrote: >At 08:50 PM 8/18/02 -0600, you wrote: >>Original poster: "Terry Fritz" > >>I could kick myself for one thing... I have no way of getting a current >>monitor in the primary circuit :-(( I have like six Pearson current >>monitors here (one is a 50,000 amp!) and no way to insert one in the >>circuit. I guest that is why they make the split clamp one types too (and >>charge 5X for them! They know when they gotcha!) >> > >Perhaps you could wind a Rogowski coil around a piece of hose or something >similar. Use your favorite opamp to make an integrator. You could calibrate >it against one of your Pearson transformers. > >some links that turned up on google: >http://homepage.ntlworld.com/rocoil/Pr9.pdf >http://www.rocoil.cwc.net/ > >Eddie Burwell > > > Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Mon, 19 Aug 2002 17:48:35 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Mon, 19 Aug 2002 17:34:50 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: Re: OLTC Update X-Mailing-List: archive/latest/1312 X-Loop: tesla@pupman.com Original poster: "bob by way of Terry Fritz " hi terry, this oltc stuff reminds me of the early days of mmc's. i cant wait to see what happens when you build the secondary and see what happens to the sparks, if any. Maybe even flames like from a vttc even. I cant seem to find any reference to the igbt's you are using?? keep up the good work. bob golding Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Mon, 19 Aug 2002 20:00:26 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Mon, 19 Aug 2002 18:25:24 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: Re: OLTC Update X-Mailing-List: archive/latest/1313 X-Loop: tesla@pupman.com Original poster: "Terry Fritz" At 07:42 AM 8/19/2002 -0500, you wrote: >Terry, ...> >As previously mentioned, a possible downside is that, through >transformer action, some of the secondary's energy will be extracted >during secondary ringdown, resulting in partial recharging of the tank >caps through the internal HexFRED diodes. But even this shouldn't be too >much of a problem since the tank caps will only recharge when the >induced tank EMF is greater than the voltage stored on the tank caps. >Since the induced primary voltage will be constrained by the >secondary-to-primary turns ratio (i.e., with the diode in the circuit >energy transfer is no longer resonant between secondary and primary), >the actual amount of power lost in this fashion should be comparatively >small. And, unlike a spark gap, the energy is not actually lost, but is >"recycled" back to the tank cap instead of being burned up. > >Great job, Terry - dang, you're getting me excited now...! > >Best regards, > >-- Bert -- >-- Hi Bert, I ran a model of this situation: http://hot-streamer.com/temp/OLTC08-19-01.gif The waveform looks like: http://hot-streamer.com/temp/OLTC08-19-02.gif There is a little recharging of the cap. Since the energy in the cap is proportional to V^2, this energy is pretty small. Compare the green output wavefrom to a perfect case: http://hot-streamer.com/temp/OLTC08-19-03.gif The coil's output does not appear to be visibly affected. So we may be fine. Just have to see what happens in real life. Cheers, Terry Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Mon, 19 Aug 2002 23:16:10 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Mon, 19 Aug 2002 22:12:19 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: OLTC update X-Mailing-List: archive/latest/1314 X-Loop: tesla@pupman.com Original poster: "Terry Fritz" Hi all, I just mostly cleaned up the construction of the primary system tonight: http://hot-streamer.com/temp/OLTC08-19-05.jpg That is pretty much the whole system minus the secondary and toroid. It weighs in at 19 pounds. I put the IGBT drivers in a metal box and all too: http://hot-streamer.com/temp/OLTC08-19-04.jpg I hope to have it running at low voltage off a variac tomorrow if all goes well. Here is the first serious power configuration: http://hot-streamer.com/temp/OLTC08-19-06.gif I have turned off Vac1 so it is running off 120 VAC. I also have a big adjustable power resistor in series with Lb which allows me to limit the voltage. In this configuration, everything is running well below it capability but it is still capable of real output power. Of course, I still have the minor detail of needing to make the secondary ;-)) Cheers, Terry Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Tue, 20 Aug 2002 23:28:20 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Tue, 20 Aug 2002 22:24:59 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: OLTC update X-Mailing-List: archive/latest/1315 X-Loop: tesla@pupman.com Original poster: "Terry Fritz" Hi All, As I write this the list server is still down. Chip knows all about it, so just a matter of time before he can "fix" it. ;-)) Tonight, I hooked up my signal generator up to my low-Z amp to power the coil circuit for preliminary testing. Something looked all messed up in the line side at first, till I went back to MicroSim. I just got all confused about ground references and such. No problem at all. But it did make may heart beat faster for awhile :-)) I quickly grew tired of the "weenie" ten volt input voltage an got out the big variac. :-)) It took a long time to verify the connections and hook up's for a seriously unlimited current voltage source. Things will explode now if I screw up :o)) But after an hour, I was sure that everything was safe and sound. So I cranked it on!! After spending three weeks starring at MicroSim models and thinking out zillions of details, I was stunned that it worked exactly like it was supposed to!!!! Here are the primary current and charging current waveforms that MicroSim kept telling me I had to "make": http://hot-streamer.com/temp/OLTC08-20-04.gif and here is how it actually turned out:-)) http://hot-streamer.com/temp/OLTC08-20-01.gif MicroSim predicted that the firing pulse delay would be about 115uS. http://hot-streamer.com/temp/OLTC08-20-05.gif It was really 132uS. http://hot-streamer.com/temp/OLTC08-20-02.gif Close enough ;-)) A trivial thing, as long as it works ;-)) This is an important test that falls under the "cheap scope tricks" category. I ran the thing and the scope overwrote the waveform 128 times with full peak detection and all the fancy stuff on to detect any "glitches". http://hot-streamer.com/temp/OLTC08-20-03.gif The signal are rock solid and clean :-)) I really really like the timing circuit!!!!! Simple, cheap, and it seems to work 100%!!! I should explain how it works some time, but not tonight ;-)) So All is going perfectly :o)) Time to think about the secondary... It may incorporate a brand new tuning trick too whose time seems to have come of age :-))) Cheers, Terry Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Wed, 21 Aug 2002 13:54:27 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Wed, 21 Aug 2002 12:17:54 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: Re: OLTC update X-Mailing-List: archive/latest/1344 X-Loop: tesla@pupman.com Original poster: "by way of Terry Fritz " Hi Terry, All, The recent developments in new types of coil systems brings up what may be (at least to me) an interesting philosophical question. At what point in evolution is a Tesla Coil no longer a Tesla coil? Just as we do not see the names Fleming or de Forest credited with cermolox transmitting tubes, or the name Shockley associated with modern solid state chips, I see little in the OLTC except for the idea of an air-core resonant transformer that can be attributed to Tesla. The OLTC uses materials, devices and concepts totally unheard of, or even guessed at, in Tesla's day. IMO the OLTC it has more differences from a Tesla coil than an "Oudin" coil has. Perhaps we are witnessing the birth of the OLFC (Off-Line Fritz Coil) or at very least the "Off-Line Fritz-Tesla System"? For two cents plain, Matt D. Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Wed, 21 Aug 2002 17:58:14 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Wed, 21 Aug 2002 17:29:06 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: RE: OLTC update X-Mailing-List: archive/latest/1351 X-Loop: tesla@pupman.com Original poster: "Lau, Gary by way of Terry Fritz " If it's not a "Tesla Coil", then discussing it would be off-topic for this List. I say let's keep the name ;-) Gary Lau MA, USA Original poster: "by way of Terry Fritz " Hi Terry, All, The recent developments in new types of coil systems brings up what may be (at least to me) an interesting philosophical question. At what point in evolution is a Tesla Coil no longer a Tesla coil? Just as we do not see the names Fleming or de Forest credited with cermolox transmitting tubes, or the name Shockley associated with modern solid state chips, I see little in the OLTC except for the idea of an air-core resonant transformer that can be attributed to Tesla. The OLTC uses materials, devices and concepts totally unheard of, or even guessed at, in Tesla's day. IMO the OLTC it has more differences from a Tesla coil than an "Oudin" coil has. Perhaps we are witnessing the birth of the OLFC (Off-Line Fritz Coil) or at very least the "Off-Line Fritz-Tesla System"? For two cents plain, Matt D. Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Wed, 21 Aug 2002 17:48:38 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Wed, 21 Aug 2002 17:32:52 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: Re: OLTC update X-Mailing-List: archive/latest/1361 X-Loop: tesla@pupman.com Original poster: "Brian by way of Terry Fritz " Next just for giggles, Terry is going to design a compact OLTC and send it into outerspace on its own simulation! Sounds like Great Ground Breaking work, glad to see it worked!!! Awesome! cul Brian F ----- Original Message ----- From: "Tesla list" To: Sent: Wednesday, August 21, 2002 12:24 AM Subject: OLTC update > Original poster: "Terry Fritz" > > Hi All, > > As I write this the list server is still down. Chip knows all about it, so > just a matter of time before he can "fix" it. ;-)) > > > Tonight, I hooked up my signal generator up to my low-Z amp to power the > coil circuit for preliminary testing. Something looked all messed up in > the line side at first, till I went back to MicroSim. I just got all > confused about ground references and such. No problem at all. But it did > make may heart beat faster for awhile :-)) I quickly grew tired of the > "weenie" ten volt input voltage an got out the big variac. :-)) > > > It took a long time to verify the connections and hook up's for a seriously > unlimited current voltage source. Things will explode now if I screw up > :o)) But after an hour, I was sure that everything was safe and sound. So > I cranked it on!! After spending three weeks starring at MicroSim models > and thinking out zillions of details, I was stunned that it worked exactly > like it was supposed to!!!! Here are the primary current and charging > current waveforms that MicroSim kept telling me I had to "make": > > http://hot-streamer.com/temp/OLTC08-20-04.gif > > and here is how it actually turned out:-)) > > http://hot-streamer.com/temp/OLTC08-20-01.gif > > > MicroSim predicted that the firing pulse delay would be about 115uS. > > http://hot-streamer.com/temp/OLTC08-20-05.gif > > It was really 132uS. > > http://hot-streamer.com/temp/OLTC08-20-02.gif > > Close enough ;-)) A trivial thing, as long as it works ;-)) > > > This is an important test that falls under the "cheap scope tricks" > category. I ran the thing and the scope overwrote the waveform 128 times > with full peak detection and all the fancy stuff on to detect any "glitches". > > http://hot-streamer.com/temp/OLTC08-20-03.gif > > The signal are rock solid and clean :-)) I really really like the timing > circuit!!!!! Simple, cheap, and it seems to work 100%!!! I should explain > how it works some time, but not tonight ;-)) > > So All is going perfectly :o)) Time to think about the secondary... It > may incorporate a brand new tuning trick too whose time seems to have come > of age :-))) > > Cheers, > > Terry > > > > > > Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Thu, 22 Aug 2002 22:19:48 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Thu, 22 Aug 2002 22:16:34 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: Re: OLTC update X-Mailing-List: archive/latest/1430 X-Loop: tesla@pupman.com Original poster: "Darren Freeman by way of Terry Fritz " At 03:47 AM 22/08/2002, you wrote: >Original poster: "by way of Terry Fritz " > > >Hi Terry, All, > The recent developments in new types of coil systems brings up > what may >be (at least to me) an interesting philosophical question. At what point in >evolution is a Tesla Coil no longer a Tesla coil? Just as we do not see the Dunno =) >names Fleming or de Forest credited with cermolox transmitting tubes, or the >name Shockley associated with modern solid state chips, I see little in the >OLTC except for the idea of an air-core resonant transformer that can be >attributed to Tesla. The OLTC uses materials, devices and concepts totally >unheard of, or even guessed at, in Tesla's day. IMO the OLTC it has more So does the VTTC or the SSTC.. When I rock up at Robin's place and drive his pole pig coil from a solid state RF supply, does it stop being a Tesla coil for the duration of the experiment? What if I completely mangled the primary circuit? What if I used a chain of converters ending in a Tesla secondary coil? I say the Tesla coil is the secondary, which we normally power with a spark-gap RF source. But is the source necessarily important? If a secondary sits on a table, it's a Tesla coil. If a primary sits on a table, it's a big air-cored inductor. If they both sit in a complete setup, they're fun to watch =) Doesn't matter where the RF comes from. Maybe the OLTC is a Fritz Generator powering a Tesla coil? >differences from a Tesla coil than an "Oudin" coil has. > Perhaps we are witnessing the birth of the OLFC (Off-Line Fritz Coil) or at >very least the "Off-Line Fritz-Tesla System"? > >For two cents plain, > >Matt D. Have fun, Darren Freeman Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Thu, 22 Aug 2002 23:40:15 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Thu, 22 Aug 2002 23:35:53 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: Re: OLTC update X-Mailing-List: archive/latest/1432 X-Loop: tesla@pupman.com Original poster: "Terry Fritz" Hi Matt, At 01:18 PM 8/21/2002 -0400, you wrote: >Hi Terry, All, > The recent developments in new types of coil systems brings up what >may be (at least to me) an interesting philosophical question. At what point >in evolution is a Tesla Coil no longer a Tesla coil? Just as we do not see >the names Fleming or de Forest credited with cermolox transmitting tubes, or >the name Shockley associated with modern solid state chips, I see little in >the OLTC except for the idea of an air-core resonant transformer that can be >attributed to Tesla. The OLTC uses materials, devices and concepts totally >unheard of, or even guessed at, in Tesla's day. IMO the OLTC it has more >differences from a Tesla coil than an "Oudin" coil has. > Perhaps we are witnessing the birth of the OLFC (Off-Line Fritz Coil) or >at very least the "Off-Line Fritz-Tesla System"? > >For two cents plain, > >Matt D. > Tesla invented these machines, there is no doubt about that ;-) He would recognize every part today, as he would have 100 years ago. Primary, secondary, spark gap.... They are all right there and serve the same function now, as then. The fancy poly caps are far advanced from his wine bottles, but we sell wine in polypropylene bags now too. I guess the technology works both ways!! :o)) Hey!! I bet those wine poly bags make great caps too!! :-))) Oh! Another "terry" invention... Hahaha!! The IGBT gap is just a spark gap with very modern components. The function is identical to Tesla's gaps. Tesla used high voltage transformers and such to force primary currents. Today, we can force the same currents at much lower (even line) voltages with more modern components. Basically, nothing has changed. We are just getting "better" at making "Tesla's" machine. "I" look at this like MMC's and E-Tesla... "I" may have gotten the ball rolling, but contributions from countless others made it "work". The very advanced C++ version of E-Tesla is something "I" could have never made. The work of many "others" made it "really work"... MMCs... Well, we just soldered "good" caps together there. The designer's of those caps spent years making them work... We just listened to them and followed their instructions for our application. We had a darn nasty application :-)) But the real designers were "right" and they met are needs ;-)) "I" have a lot of time and money to "blow" on this hobby of Tesla coiling. I guess "fate" as defined that as "my" niche... I am certainly not working in any vacuum. Garry Freemyer contributed a tremendous amount of time and effort to his skills at being able to kill any Tesla coil cap just by "looking" at it. When we could make an MMC that "Garry" could not break, we "had" something :-))) So, today, it is impossible to attribute anything to any one person in this area of Tesla coiling. As a Tesla list "group", we "all" are the inventors and innovators. Terry may sometimes put on the "cheerleaders" uniform and chant the "raw raw chish boom bah, OLTCs are HOT now!, boom bah" thing... But it is really all the work of others that make it work... Our greatest advantage over Tesla is that we don't have to impress any J.P. Morgan for funds. Tesla had a great obligation to "find" money to support his efforts. Today, we can draw off modern technologies "dirt cheap"... So, none of this can be blamed on "me". Cheers, terry Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Sat, 24 Aug 2002 23:03:47 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Sat, 24 Aug 2002 23:02:13 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: OLTC update X-Mailing-List: archive/latest/1501 X-Loop: tesla@pupman.com Original poster: "Terry Fritz" Hi All, Today I set up the coil for action: http://hot-streamer.com/temp/OLTC08-24-02.jpg I powered up the coil at low power and brought the coil into tune by selecting toroids and the distance they were above the coil. I ended up with one of Finn's toroids about 8 inches from the top of the coil. I brought the coil up at low power. The first notch timing was way off. Instead of being about 102uS it was closer to only 45uS. The ring up was also far faster than anticipated: http://hot-streamer.com/temp/OLTC08-24-01.gif I ran a bunch of MicroSim models and determined that the coupling was an astounding ~0.30 Far higher than anticipated. Apparently, single turn primary coils (or single coils with three spread conductors like this coils uses) are capable of very high coupling. I tried raising the secondary but the coupling tended to stay very high. I could raise the coil to get it to about 0.15 but the power of the coil obviously diminished. Realizing that this problem would need considerable more study (and time), I went ahead with the other testing. I was able to lock a dwell timing on the first notch despite the fast time. The spike protection circuit of yesterday was obviously working. I was getting a small electrostatics shock off the adjustment knob and low power but just since I was close to the coil. All else seemed well so I removed sensitive test equipment from the area. As the power increased, the machine seemed to almost shake the room. Even though there was no spark gap firing, the caps and coil had a profound electrostatic sound to them. Slowly turning up the power I go the first arc. However, it was primary to secondary corona. The plastic stretch wrap is obviously a very good insulator! I fiddled with the tuning a bit more and placed a piece of G-10 between the IGBT array and the secondary. This allowed me to turn up the coil for the first small streamer action: http://hot-streamer.com/temp/OLTC08-24-03.jpg I turned up the power more until I got streamers about twice this size at about 5 inches. I was just about to snap the camera when it made an "odd" sound. I turned it off instantly. I found no obvious damage and the coil repowered fine. I think it was either corona breaking out somewhere I didn't see, possibly a larger streamer, or a loss of control in the electronics. Definitely a "different" sound. So I ran a little longer at lower power to confirm there was no damage and shut down. I was unable to work on it for the rest of the day. Due to other commitments I am going to look at the "flight recorder" video tonight and think on things. So it is basically working :-)) The coupling is probably a bit of a messy issue I need to look into. The primary to secondary spacing may be too small too. The coil was happily arcing to the IGBT array and all with no damage. Other than the possible late problem, all the control electronics seem to perform perfectly. So, I really didn't get much time to work on it, but it went pretty well. Cheers, Terry Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Sun, 25 Aug 2002 11:11:32 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Sun, 25 Aug 2002 11:08:54 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: Re: OLTC update X-Mailing-List: archive/latest/1512 X-Loop: tesla@pupman.com Original poster: "K. C. Herrick by way of Terry Fritz " Terry (& all)- I've been following the OLTC saga off & on. But it's just occurred to me that you may find yourself up against the situation I've found with my s.s. coil: As you may recall, I apply a ~1200 V pp square-wave burst, of up to ~6 ms duration, to a 3-turn (untuned) primary circuit for each spark. With a 140 KHz secondary Fr and a 6" x 24" smooth (Landergren) toroid, it takes ~30 cycles of constant (not exponentially declining!) excitation to bring the toroid potential up to the spark break-out level. You are applying, I believe, ~680 x 2.8 = ~1900 V pp, initially, to a 3-turn primary circuit--incorporating much less resistance, admittedly, than mine--but your excitation must (necessarily) exponentially-decline quite rapidly. I'd think you might require more or less those 30 cycles to pump up the voltage & I fear that the decline of your primary voltage may preclude that. Were you able to do any simulations on that? Ken Herrick On Sat, 24 Aug 2002 23:02:13 -0600 "Tesla list" writes: > Original poster: "Terry Fritz" > > Hi All, > > Today I set up the coil for action: > > http://hot-streamer.com/temp/OLTC08-24-02.jpg > > I powered up the coil... [snipped] Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Mon, 26 Aug 2002 13:06:14 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Mon, 26 Aug 2002 13:01:04 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: OLTC update X-Mailing-List: archive/latest/1567 X-Loop: tesla@pupman.com Original poster: "Terry Fritz" Hi Everyone, Many thinks for all the kind words :-)) I thought I would be ordering replacement FETs and pondering "what happened" today :o)) I have found that I set the secondary capacitance to 37.3pF in error last night. It should have been 30.5pF. The secondary frequency was 34.7kHz instead of 38.3 like it should have been. So the tuning was 10% off in frequency resulting in only 25% power to an air streamer. That explains the short streamers to air but big arcs to ground. I may have to pull a few turns off the secondary eventually. The primary inductance is only like 410nH! That is how I am getting such a nice high Fo frequency. I think the coupling needs to be around 0.10. The input power was about 225 watts. The IGBT heatsink got just slightly warm (30C) with a long run. If the coil is not breaking out, I really have no idea where the power goes. Perhaps into secondary heating. So I'll tune things up and work on it some more to see if the streamers perform more as expected. I will be writting all this up too. I will probably get everything running at 120VAC and do destructive IGBT testing before going up to 240VAC. Now that the coil is working, I find I would like to keep it that way ;-)) Cheers, Terry Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Mon, 26 Aug 2002 17:28:37 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Mon, 26 Aug 2002 17:21:59 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: Re: OLTC update X-Mailing-List: archive/latest/1573 X-Loop: tesla@pupman.com Original poster: "Antonio Carlos M. de Queiroz by way of Terry Fritz " Tesla list wrote: > > Original poster: "Terry Fritz" First of all, congratulations for the nice work. > I have found that I set the secondary capacitance to 37.3pF in error last > night. It should have been 30.5pF. The secondary frequency was 34.7kHz > instead of 38.3 like it should have been. So the tuning was 10% off in > frequency resulting in only 25% power to an air streamer. That explains > the short streamers to air but big arcs to ground. k=0.095 is mode 10-11, with 5.5 cycles for energy transfer. Tuning starts to be critical, but 10% of error would make little difference. An interesting question is how the tuning affects the voltage gain. The tuning becomes more critical when the coupling is low. Note that the presence of the other terminal, that receives the arcs, causes significant mistuning, and even the presence of the breakout wire can make a little change. > I may have to pull a > few turns off the secondary eventually. The primary inductance is only > like 410nH! That is how I am getting such a nice high Fo frequency. I > think the coupling needs to be around 0.10. The input power was about 225 > watts. The IGBT heatsink got just slightly warm (30C) with a long run. If > the coil is not breaking out, I really have no idea where the power goes. > Perhaps into secondary heating. I like to see this by observing the primary voltage without quenching. The presence of deep notches shows that the tuning is correct, and the peak of the first beat maximum after the first notch indicates how much energy was transferred back from the secondary. Interpolate between the initial energy and this energy and you have an approximation of how much energy was transferred to the secondary at the first notch. Here for example: http://www.coe.ufrj.br/~acmq/tesla/vc1910.jpg The voltage at the second beat peak is approximately 3/4 of the intial voltage, indicating that 9/16 = 0.56 of the initial energy returned. The energy that was transferred at the first notch is then ((1+3/4)/2)^2 = 0.77 of the initial energy, approximately. > So I'll tune things up and work on it some more to see if the streamers > perform more as expected. I will be writting all this up too. I will > probably get everything running at 120VAC and do destructive IGBT testing > before going up to 240VAC. Now that the coil is working, I find I would > like to keep it that way ;-)) It's easy to tune a coil at low power by observing the primary voltage. Just adjust the top load until you see deep notches. Approach your hand to the terminal to see if you need more or less capacitance. At -low- power, of course. Losses don't affect much the tuning. Antonio Carlos M. de Queiroz Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Mon, 26 Aug 2002 22:50:06 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Mon, 26 Aug 2002 22:44:47 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: Re: OLTC update X-Mailing-List: archive/latest/1600 X-Loop: tesla@pupman.com Original poster: "Bert Hickman by way of Terry Fritz " Hi Terry, Way to go - congratulations on a very successful "first light" (and not even a single IGBT carcass!)! Now "all" you need to do is bump the coupling coefficient up to say 0.153, 0.18, 0.22, or even stretch it to 0.28 (heavans - a complete P-S transfer in 2 cycles!) to further reduce primary losses. This could evolve to be an E-field versus coupling coefficient design challenge. The trick will be to do this without resorting to oil insulation... :^). If you're using industrial grade "stretch wrap", it can be any of the following - High Density Polyethylene (HDPE), Low Density Polyethylene (LDPE), Polypropylene Film, or linear low density polyethylene (LLDPE) - all make excellent insulating films. If you're using plain old Saran Wrap, then it's Polyvinylidene Chloride - not as good as the PE or PP films, and the higher dielectric constant may actually worsen breakdown of the air space. And, if you get a chance, try to capture that "blue glow" in a shot or two... :^) -- Bert -- -- Bert Hickman Stoneridge Engineering "Electromagically" Shrunken Coins! http://www.teslamania.com Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Tue, 27 Aug 2002 22:21:45 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Tue, 27 Aug 2002 22:18:09 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: OLTC update X-Mailing-List: archive/latest/1651 X-Loop: tesla@pupman.com Original poster: "Terry Fritz" Hi All, I took yesterday off from the OLTC thing to "recover" ;-)) But today I was back at it. First I ran countless MicroSim and E-Tesla6 runs to tell me how to fix the tuning problem. It was tuned 10% low before and I could not tune to coil to the right place by moving the toroid up and down. I found my answer and hack sawed 5 inches off the secondary with no fear! I should have taken a picture of me sawing away "tuning" my coil :o)) I guess I am getting pretty good at that stuff since it turned out perfectly :-)) I can now tune anything again just my moving the toroid up and down. So I turned my attention to the fast ring up problem again. It didn't go away like it was supposed to. The coil really does have very fast ring up even at higher power levels as the no-quench yellow scope trace here shows: http://hot-streamer.com/temp/OLTC08-27-01.gif A few minute with MicroSim gave the answer: http://hot-streamer.com/temp/OLTC08-27-02.gif Primary circuit loss is 2.5 mOhm which is right on target at these low power levels but the coupling REALLY IS 0.25! I could never quite "see" or visualize how coupling works, but I guess I did something right. The primary to secondary coupling in my OLTC is enormous. I don't know if it is the three parallel loops give very low primary inductance or what... This 0.25 number is "with" the secondary being raised as show here (note the shorter secondary now)! http://hot-streamer.com/temp/OLTC08-27-04.jpg So for some reason, this coil has very high coupling. I don't know if this is good or bad... I guess it is good since I can always reduce it and I seem to be able to easily control racing arcs and primary to secondary arcs at this level. So I just need to find a sweet spot and adjust things for it. I see Marco has just published an article in a prestigious scientific journal on this very subject :-)))) I will have to read it again and try to understand it this time :o)) The present schematic for the coil is at: http://hot-streamer.com/temp/OLTC08-27-03.gif This model tends to have errors during runs that I fiddle with to work around but it seems to be predicting things perfectly! A giant help in the case of these very odd machines... Once I get these details worked out and the weather is nice, I will haul all 35 pounds of it outside and let it loose! Then I can work on pumping it up to 4X the power running off 240VAC like it is really supposed too :-))) BTW - Many many thanks for everyone's kind comments in all this. It easily could have been an embarrassing disaster! It would have taken me almost a whole day to get over that :o))) But it looks like I got lucky this time :-)) Also, many thanks for all the great ideas people have suggested that really made this thing work! I have been posting virtually every detail to the list here, but I will also write it all up when the dust settles. Cheers, Terry Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Wed, 28 Aug 2002 08:22:33 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Wed, 28 Aug 2002 08:12:59 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: Re: OLTC update X-Mailing-List: archive/latest/1658 X-Loop: tesla@pupman.com Original poster: "Eddie Burwell by way of Terry Fritz " Terry, My take on coupling is basically that it is a function of proximity. The turns that are close are tightly coupled, and the turns that are distant are weakly coupled and add leakage inductance that serves to decrease K. Taken to the high coupling extreme we have pulse transformers where the secondary is basically wrapped in a sheet of copper making one turn for the primary. The primary is in close proximity to all turns of the secondary and therefore the leakage inductance is low. I believe your triple primary is in close proximity to a larger than usual number of turns (for a flat spiral) and K is higher as a result. OLTC Maggie? OLTC-HEIC? OLTC-HEIC Maggie?? Waiting on the edge of my seat for the full power test! Eddie Burwell At 10:18 PM 8/27/02 -0600, you wrote: >Original poster: "Terry Fritz" > >Primary circuit loss is 2.5 mOhm which is right on target at these low >power levels but the coupling REALLY IS 0.25! I could never quite "see" or >visualize how coupling works, but I guess I did something right. The >primary to secondary coupling in my OLTC is enormous. I don't know if it >is the three parallel loops give very low primary inductance or what... >This 0.25 number is "with" the secondary being raised as show here (note >the shorter secondary now)! > >http://hot-streamer.com/temp/OLTC08-27-04.jpg > >So for some reason, this coil has very high coupling. I don't know if this >is good or bad... I guess it is good since I can always reduce it and I >seem to be able to easily control racing arcs and primary to secondary arcs >at this level. So I just need to find a sweet spot and adjust things for it. > >I see Marco has just published an article in a prestigious scientific >journal on this very subject :-)))) I will have to read it again and try >to understand it this time :o)) > Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Wed, 28 Aug 2002 12:01:48 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Wed, 28 Aug 2002 11:47:46 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: Re: OLTC update X-Mailing-List: archive/latest/1661 X-Loop: tesla@pupman.com Original poster: "jimmy hynes by way of Terry Fritz " i agree with eddie on this. the number of turns shouldnt effect k unless you had alot of stray inductance from the wires going to the igbts and caps, it looks like you kept that really low the way you set it up. your primary basically couples like a cylindrical primary. Tesla list wrote: > > Original poster: "Eddie Burwell by way of Terry Fritz " > > Terry, > My take on coupling is basically that it is a function of proximity. The > turns that are close are tightly coupled, and the turns that are distant are > weakly coupled and add leakage inductance that serves to decrease K. Taken > to the high coupling extreme we have pulse transformers where the secondary > is basically wrapped in a sheet of copper making one turn for the primary. > The primary is in close proximity to all turns of the secondary and > therefore the leakage inductance is low. I believe your triple primary is in > close proximity to a larger than usual number of turns (for a flat spiral) > and K is higher as a result. > > OLTC Maggie? > OLTC-HEIC? > OLTC-HEIC Maggie?? > > Waiting on the edge of my seat for the full power test! > > Eddie ! Burwell > > > > > At 10:18 PM 8/27/02 -0600, you wrote: > >Original poster: "Terry Fritz" > > > > >Primary circuit loss is 2.5 mOhm which is right on target at these low > >power levels but the coupling REALLY IS 0.25! I could never quite "see" or > >visualize how coupling works, but I guess I did something right. The > >primary to secondary coupling in my OLTC is enormous. I don't know if it > >is the three parallel loops give very low primary inductance or what... > >This 0.25 number is "with" the secondary being raised as show here (note > >the shorter secondary now)! > > > >http://hot-streamer.com/temp/OLTC08-27-04.jpg > > > >So for some reason, this coil has very high coupling. I don't know if this > >is good or bad... I guess it is good since I can always reduce it and I > >seem to be able to easily control racing arcs and primary to secondary arcs > >at this level. So! I just need to find a sweet spot and adjust things for > it. > ! > > >I see Marco has just published an article in a prestigious scientific > >journal on this very subject :-)))) I will have to read it again and try > >to understand it this time :o)) > > > JImmy Do You Yahoo!? Yahoo! Finance - Get real-time stock quotes Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Wed, 28 Aug 2002 12:40:10 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Wed, 28 Aug 2002 12:34:44 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: OLTC update X-Mailing-List: archive/latest/1666 X-Loop: tesla@pupman.com Original poster: "Terry Fritz" Hi All, I ran various MicroSim models with K going from 0.05 to 0.25 with primary resistances of 0.5, 1.5, and 2.5 mOhms. I found the resulting peak secondary voltages: http://hot-streamer.com/temp/OLTC08-28-01.gif http://hot-streamer.com/temp/OLTC08-28-02.gif I think the dip in the yellow line at 13 is a mistake in my data. In the low loss (r=0.0005) case you can see the effect of sweet spots above k=0.20. It's sort of neat in that you can see the affects of primary resistance, self quenching, and "some" of the sweet spots Marco and Antonio speak of. I guess I have to disagree a little on the sweet spot thing since those analyses do not take into account Rs, Rp, or streamer loading. If the coil is really efficient, the sweet spots become more important. But for a coil with typical loss, other factors tend to overshadow the sweet spots. Note that high coupling is not always the best as in this case. But I have a great advantage in being able to quench at any time too. That actually adds about 76% to the streamer power! It also reduces the stress on the IGBTs which is getting to be an issue. So it looks like a k of 0.115 is optimal with a dwell time of 102.5uS. http://hot-streamer.com/temp/OLTC08-28-03.gif I will raise the secondary tonight for this. Not that I am quenching while the voltage on the caps is negative to help "push" the resonant charging. This is also a zero current crossing which eases IGBT and TVS stresses from the primary coil kicking back. The latest schematic is at: http://hot-streamer.com/temp/OLTC08-28-04.gif I also have a chart showing the line voltage and current here: http://hot-streamer.com/temp/OLTC08-28-05.gif The line noise and power factor are excellent. The coil has an input power of 286 watts right now at 120VAC. I'll pick up some 2.5 amp fuses today too. One thing that is a little scarry is that the IGBTs will see a 3356 amp peak current. Their rating is 2040 amps. I am pretty sure I will be OK now at 120VAC but at 240VAC, the peak current will get near 4500 amps! I will order up some more IGBTs today for my peak current testing. I may need more IGBTs since 450 amps is over twice the rated peak current. I'll just have to test some and see... Cheers, Terry Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Wed, 28 Aug 2002 16:21:14 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Wed, 28 Aug 2002 16:13:06 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: Re: OLTC update X-Mailing-List: archive/latest/1671 X-Loop: tesla@pupman.com Original poster: "Malcolm Watts by way of Terry Fritz " Hi Terry, On 28 Aug 2002, at 12:34, Tesla list wrote: > Original poster: "Terry Fritz" > > Hi All, > > I ran various MicroSim models with K going from 0.05 to 0.25 with primary > resistances of 0.5, 1.5, and 2.5 mOhms. I found the resulting peak > secondary voltages: > > http://hot-streamer.com/temp/OLTC08-28-01.gif > > http://hot-streamer.com/temp/OLTC08-28-02.gif > > I think the dip in the yellow line at 13 is a mistake in my data. In the > low loss (r=0.0005) case you can see the effect of sweet spots above k=0.20. > > It's sort of neat in that you can see the affects of primary resistance, > self quenching, and "some" of the sweet spots Marco and Antonio speak of. > I guess I have to disagree a little on the sweet spot thing since those > analyses do not take into account Rs, Rp, or streamer loading. If the coil > is really efficient, the sweet spots become more important. But for a coil > with typical loss, other factors tend to overshadow the sweet spots. > > Note that high coupling is not always the best as in this case. But I have > a great advantage in being able to quench at any time too. That actually > adds about 76% to the streamer power! It also reduces the stress on the > IGBTs which is getting to be an issue. > > So it looks like a k of 0.115 is optimal with a dwell time of 102.5uS. > > http://hot-streamer.com/temp/OLTC08-28-03.gif > > I will raise the secondary tonight for this. Not that I am quenching while > the voltage on the caps is negative to help "push" the resonant charging. > This is also a zero current crossing which eases IGBT and TVS stresses from > the primary coil kicking back. > > The latest schematic is at: > > http://hot-streamer.com/temp/OLTC08-28-04.gif > > I also have a chart showing the line voltage and current here: > > http://hot-streamer.com/temp/OLTC08-28-05.gif > > The line noise and power factor are excellent. The coil has an input power > of 286 watts right now at 120VAC. I'll pick up some 2.5 amp fuses today too. > > One thing that is a little scarry is that the IGBTs will see a 3356 amp > peak current. Their rating is 2040 amps. I am pretty sure I will be OK > now at 120VAC but at 240VAC, the peak current will get near 4500 amps! I > will order up some more IGBTs today for my peak current testing. I may > need more IGBTs since 450 amps is over twice the rated peak current. I'll > just have to test some and see... Each IGBT is discharging an individual cap isn't it? If that's the case, then the only ways of alleviating the stress on the devices is to start paralleling them with others or reduce the capacitance associated with each. Re the coupling, Eddie Burwell has it. Could you post a url for an oscillogram of the primary ringing alone please? I don;t have time to wade through all the urls you post unfortunately (my problem, not yours ;) Regards, Malcolm Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Wed, 28 Aug 2002 16:58:25 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Wed, 28 Aug 2002 16:53:29 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: Re: OLTC update X-Mailing-List: archive/latest/1675 X-Loop: tesla@pupman.com Original poster: "Terry Fritz" Hi Malcolm, At 08:28 AM 8/29/2002 +1200, you wrote: >Hi Terry, ............. > >Each IGBT is discharging an individual cap isn't it? If that's the >case, then the only ways of alleviating the stress on the devices is >to start paralleling them with others or reduce the capacitance >associated with each. Yes, each IGBT has it's own cap to control current sharing. I could use twice as many IGBT/cap sets with caps of 1/2 the value and cut the current each IGBT sees in half. However, I designed a "tester" today that can run a single IGBT up to destruction that simulates my real coil's current waveforms. So I can find exactly how much current they can take with my coil's pulse pattern. I know they can take "more" than the data sheets say. I am just not sure if it is 10% more or 5000% more... IR just gives guaranteed specs under just about any condition. If one wants to run them higher in some particular application like mine, "I" have to do the work to find the specs in that case... The fewer IGBT/caps needed make the thing cheaper. I guess an "E"MMIGBT array :o)) In our non-"life or death" hobby Tesla coil application, we are allowed to run them at "destruct level - 1%" :o)) Some folks I have talked with say that since the die are only slightly above room temperature, the duty cycle is low and slow, the life time can be "only" hours, the application is not-"critical" and the oscillations divide the stress between the IGBT and the anti-parallel diodes... all add up to being able to drive the IGBTs at "wildly high" peak currents... Nobody knows how high. I plan on finding out :-))) They do warn to be careful of Ccg shoot through but that is mostly a high collector dV/dT problem not a giant current problem. I have some really fancy TVSs if that turns out to be a problem but I can still slow the switching down too which is probably easier if needed. I don't think it is... > > Re the coupling, Eddie Burwell has it. Could you post a url for >an oscillogram of the primary ringing alone please? I don't have time >to wade through all the urls you post unfortunately (my problem, not >yours ;) Cool! http://home.hiwaay.net/~eburwell/ I have not seen this before! Looks like Eddie is using an SCR to do something similar to my coil. I will check this out! I am planning on changing the ring up pattern drastically tonight. So don't worry too much about "todays" patterns since they may be all different "tomorrow" :o)) Cheers, Terry > >Regards, >Malcolm > Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Wed, 28 Aug 2002 20:26:24 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Wed, 28 Aug 2002 20:20:55 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: Re: OLTC update X-Mailing-List: archive/latest/1685 X-Loop: tesla@pupman.com Original poster: "Antonio Carlos M. de Queiroz by way of Terry Fritz " Tesla list wrote: > > Original poster: "Terry Fritz" > > Hi All, > > I ran various MicroSim models with K going from 0.05 to 0.25 with primary > resistances of 0.5, 1.5, and 2.5 mOhms. I found the resulting peak > secondary voltages: > > http://hot-streamer.com/temp/OLTC08-28-01.gif > > http://hot-streamer.com/temp/OLTC08-28-02.gif > > I think the dip in the yellow line at 13 is a mistake in my data. In the > low loss (r=0.0005) case you can see the effect of sweet spots above k=0.20. The results seem strange. Increasing the coupling should always reduce the loss, increasing the maximum secondary voltage. The sweet spots don't make great difference at these levels of coupling. The large increase observed for low coupling is very strange. Are you sure that you are measuring the output voltage with both polarities? Antonio Carlos M. de Queiroz Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Thu, 29 Aug 2002 18:20:56 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Thu, 29 Aug 2002 18:15:12 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: Re: OLTC update X-Mailing-List: archive/latest/1715 X-Loop: tesla@pupman.com Original poster: "Darren Freeman by way of Terry Fritz " Terry, At 04:31 AM 27/08/2002, you wrote: >Original poster: "Terry Fritz" > >watts. The IGBT heatsink got just slightly warm (30C) with a long run. If >the coil is not breaking out, I really have no idea where the power goes. >Perhaps into secondary heating. Where does the power go... Reminds me of an article in New Scientist years ago in which two scientists were trying microwave heating for the home.. They had a metal room with an essentially open microwave oven mounted in one wall.. One guy would sit inside on a sofa while the other one was operating the controls (must be pretty trusting!). The conclusion was that microwave heating was very effective as it heats the body and not the rest of the room, but there were concerns that extremities would receive greater power than the rest of the body.. So they recommended that men who want to have children one day shouldn't be trying this until more results were known =) And so I think perhaps for similar reasons we should also be concerned with where the power goes... =) >Cheers, > > Terry Have fun, stay fertile, Darren Freeman Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Tue, 17 Sep 2002 12:48:53 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Tue, 17 Sep 2002 12:32:01 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: RE: OLTC update X-Mailing-List: archive/latest/2771 X-Loop: tesla@pupman.com Original poster: "Richard Wayne Wall by way of Terry Fritz " Hi Terry and list, A sort of eerie silence has replaced all the initial excitement of the OLTC on the Tesla list. Any further progress? I recommend reading R. Hull's treatise on the optimum switch for Tesla coils. There are several important parameters that must be observed. RWW --- Richard Wayne Wall --- rwall@ix.netcom.com Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Tue, 17 Sep 2002 12:51:54 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Tue, 17 Sep 2002 12:42:21 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: RE: OLTC update X-Mailing-List: archive/latest/2778 X-Loop: tesla@pupman.com Original poster: "Terry Fritz" Hi Richard, At 12:31 PM 9/17/2002 -0700, you wrote: >Hi Terry and list, > >A sort of eerie silence has replaced all the initial excitement of the OLTC >on the Tesla list. Any further progress? > I have been looking into ways to make the next one, doing testing, looking into ideas... Sort of time consuming not too exciting stuff at the moment. Many of the desing changes take a lot of modeling to see if they would work and that takes a lot of time. Mostly looking into Ken's ideas and some thoughts Richie had. Parts for the new inductor should be here today for running at 240VAC too. So a lot of "work" going on but not to much progress to report yet ;-)) Cheers, Terry Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Tue, 17 Sep 2002 17:13:41 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Tue, 17 Sep 2002 16:57:36 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: RE: OLTC update X-Mailing-List: archive/latest/2795 X-Loop: tesla@pupman.com Original poster: "Richard Wayne Wall by way of Terry Fritz " Terry, > Mostly looking into Ken's ideas and some thoughts Richie had. Those two guys are real solid and you can't go wrong there. Basically, with my Mother's recent illness and death I've been out of the TC loop for about six weeks. I do have some ideas that I will publish to the list in the near future. I don't have a web site and have not figured out the best format yet. I'll probably just do a simple serial write up and post them. I've enjoyed your OLTC work very much. RWW --- Richard Wayne Wall --- rwall@ix.netcom.com Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Thu, 19 Sep 2002 19:30:32 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Thu, 19 Sep 2002 19:27:49 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: RE: OLTC update X-Mailing-List: archive/latest/2900 X-Loop: tesla@pupman.com Original poster: "Terry Fritz" Hi Larry, My trigger circuit does that right now :-)) This circuit works very very well and i am totally happy with it!!! I am now thinking of going to 240BPS (as suggested by Ritchie) that the trigger circuit adapts to automatically. Cheers, Terry At 02:43 AM 9/19/2002 +0000, you wrote: >Terry, > this seems like it would take the fun out of it, >but could a circuit be designed to automatically tune the oltc coil? >perhaps by monitoring current draw on the primary and varying within >a range of dwell time and searching for max current? > >larry. > > >_ Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Fri, 20 Sep 2002 17:31:56 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Fri, 20 Sep 2002 17:28:50 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: OLTC update X-Mailing-List: archive/latest/2975 X-Loop: tesla@pupman.com Original poster: "Terry Fritz" Hi All, Although I have been a bit lazy lately ;-) I still am working on the OLTC quite hard. Much of the work right now is very time consuming trying models and stuff. Pretty boring especially when the results are not significant... Also been playing with streamer currents and such. Also fixing blown fiber probes as a result ;-)) I decided not to pursue the cascade Marx configuration right now. Seems just to complex and Ken points out some problems that would be messy to fix. That configuration is very interesting indeed! But too far different from what I have now. It would need a multi turn primary and the caps would probably have to be charged through very large inductors or transistors. Primary losses may also be a problem since fewer IGBTs and four in series now... I am also holding off on the OLTC-2 effort until I can find out more about streamer loads. Even though the losses are high right now, The early streamer data seems to suggest that it is not that terrible of a problem. So I am going to learn more before changing the configuration much. I don't want to do a be redesign and find out I didn't accomplish much. I was considering rewinding the secondary on a plastic form but the data say to wait for now till I really know what the benefits will be... The thing I am really excited about right now is I think I found a way to get rid of the iron core split 150mH inductor and increase power!! By changing the inductor to an air core 34mH coil, I can run at 240BPS. Nothing else changes but the inductor. The control circuit will automatically lock on at 240Hz and run just fine. I need to use #20 wire to keep the resistance down but since I only need 34mH that is not a great problem now. Many thanks to Richie Burnett for clueing me on to this!! This also eliminates saturation problems and gives very "nice" inductance properties. The schematic is at: http://hot-streamer.com/temp/OLTC09-20-01.gif The charging waveform looks like it did before but now I have an extra smaller bang between them: http://hot-streamer.com/temp/OLTC09-20-02.gif The current is nicely balanced still: http://hot-streamer.com/temp/OLTC09-20-03.gif The line current gets strange now but it won't hurt anything. So hopefully I will get more power, 10 pounds lighter, and simpler (no split inductor just a coil of wire now). All for free basically ;-)) So I'll order up a 1000 feet of #18 wire (and a few miles of #26 in case I redo the secondary)and get it going at 240 BPS. I am interested if anyone has any tips on how to wind a 34mH air core inductor with #20 wire using the least amount of wire (least resistance). I figure a very short large diameter coil? Cheers, Terry Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Sun, 22 Sep 2002 17:56:30 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Sun, 22 Sep 2002 17:44:43 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: Re: OLTC update X-Mailing-List: archive/latest/3044 X-Loop: tesla@pupman.com Original poster: "Malcolm Watts by way of Terry Fritz " Hi Terry, On 20 Sep 2002, at 17:28, Tesla list wrote: > Original poster: "Terry Fritz" > > Hi All, > > Although I have been a bit lazy lately ;-) I still am working on the OLTC > quite hard. Much of the work right now is very time consuming trying > models and stuff. Pretty boring especially when the results are not > significant... Also been playing with streamer currents and such. Also > fixing blown fiber probes as a result ;-)) > > I decided not to pursue the cascade Marx configuration right now. Seems > just to complex and Ken points out some problems that would be messy to > fix. That configuration is very interesting indeed! But too far different > from what I have now. It would need a multi turn primary and the caps > would probably have to be charged through very large inductors or > transistors. Primary losses may also be a problem since fewer IGBTs and > four in series now... > > I am also holding off on the OLTC-2 effort until I can find out more about > streamer loads. Even though the losses are high right now, The early > streamer data seems to suggest that it is not that terrible of a problem. > So I am going to learn more before changing the configuration much. I > don't want to do a be redesign and find out I didn't accomplish much. I > was considering rewinding the secondary on a plastic form but the data say > to wait for now till I really know what the benefits will be... > > The thing I am really excited about right now is I think I found a way to > get rid of the iron core split 150mH inductor and increase power!! By > changing the inductor to an air core 34mH coil, I can run at 240BPS. > Nothing else changes but the inductor. The control circuit will > automatically lock on at 240Hz and run just fine. I need to use #20 wire > to keep the resistance down but since I only need 34mH that is not a great > problem now. Many thanks to Richie Burnett for clueing me on to this!! > This also eliminates saturation problems and gives very "nice" inductance > properties. > > The schematic is at: > > http://hot-streamer.com/temp/OLTC09-20-01.gif > > The charging waveform looks like it did before but now I have an extra > smaller bang between them: > > http://hot-streamer.com/temp/OLTC09-20-02.gif > > The current is nicely balanced still: > > http://hot-streamer.com/temp/OLTC09-20-03.gif > > The line current gets strange now but it won't hurt anything. So hopefully > I will get more power, 10 pounds lighter, and simpler (no split inductor > just a coil of wire now). All for free basically ;-)) > > So I'll order up a 1000 feet of #18 wire (and a few miles of #26 in case I > redo the secondary)and get it going at 240 BPS. > > I am interested if anyone has any tips on how to wind a 34mH air core > inductor with #20 wire using the least amount of wire (least resistance). > I figure a very short large diameter coil? The highest inductance per length of wire is scored with highest coupling between all turns. Therefore, a multi-layer coil with the number of layers = number of turns per layer is the way to go. Regards, Malcolm Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Sun, 22 Sep 2002 17:59:49 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Sun, 22 Sep 2002 17:54:55 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: Re: OLTC update X-Mailing-List: archive/latest/3048 X-Loop: tesla@pupman.com Original poster: "Terry Fritz" Hi Malcolm, At 09:03 AM 9/23/2002 +1200, you wrote: >Hi Terry, > .... > >The highest inductance per length of wire is scored with highest >coupling between all turns. Therefore, a multi-layer coil with the >number of layers = number of turns per layer is the way to go. > >Regards, >Malcolm > Yes, I did find the having the length and depth of the winding being equal was best. However, I was a long way off from where I needed to be. Had to use a split core after all ;-)) Cheers, Terry Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Sun, 22 Sep 2002 20:50:28 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Sun, 22 Sep 2002 20:46:08 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: Re: OLTC update X-Mailing-List: archive/latest/3049 X-Loop: tesla@pupman.com Original poster: "by way of Terry Fritz " In a message dated 9/22/02 7:54:53 PM Eastern Daylight Time, tesla@pupman.com writes: > > > I am interested if anyone has any tips on how to wind a 34mH air core > > inductor with #20 wire using the least amount of wire (least resistance). > > I figure a very short large diameter coil? > > The highest inductance per length of wire is scored with highest > coupling between all turns. Therefore, a multi-layer coil with the > number of layers = number of turns per layer is the way to go. Hi All, It can be shown that the highest achievable inductance for a given length of wire for a helical coil occurs when Height= 0.9 x Radius. There is a similar maximum for a flat coil at 8R=11B. I can send you a paper showing the derivations, if you desire. Matt D. Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Mon, 23 Sep 2002 07:29:35 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Mon, 23 Sep 2002 07:14:51 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: Re: OLTC update X-Mailing-List: archive/latest/3060 X-Loop: tesla@pupman.com Original poster: "Malcolm Watts by way of Terry Fritz " Hi Matt, On 22 Sep 2002, at 20:46, Tesla list wrote: > Original poster: "by way of Terry Fritz " > > In a message dated 9/22/02 7:54:53 PM Eastern Daylight Time, tesla@pupman.com > writes: > > > > > > > I am interested if anyone has any tips on how to wind a 34mH air core > > > inductor with #20 wire using the least amount of wire (least resistance). > > > I figure a very short large diameter coil? > > > > The highest inductance per length of wire is scored with highest > > coupling between all turns. Therefore, a multi-layer coil with the > > number of layers = number of turns per layer is the way to go. > > > Hi All, > It can be shown that the highest achievable inductance for a given length of > wire for a helical coil occurs when Height= 0.9 x Radius. There is a similar > maximum for a flat coil at 8R=11B. I can send you a paper showing the > derivations, if you desire. > Matt D. I derived it myself some time ago ;) However, the question was about maximum inductance for a length of wire which translates the query into the optimum coil shape which is neither a helix or flat spiral. Regards, Malcolm Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Mon, 30 Sep 2002 00:19:43 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Mon, 30 Sep 2002 00:16:07 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: OLTC update X-Mailing-List: archive/latest/3446 X-Loop: tesla@pupman.com Original poster: "Terry Fritz" Hi All, Tonight we had our Tesla meet and I ran the OLTC coil in the 240 PBS mode with the new 33mH resonant inductor. A few minor adjustments and it ran perfectly throughout. I was worried that the new mode my be unstable, but it proved to work perfectly fine. This new inductor has the current capacity to go to 240VAC and it only weighs 4 pounds. The whole coil is at 40 pounds now. 25 of that is in the controller, secondary, and top terminal. My top priority now is to gear it up for full 240VAC operation. It has only run in the 1/4 power mode (120VAC) so far and Bill's lab only has 120 VAC right now due to an "odd" wiring system. The things I need to change are: 1. Fuses need to be 7 amp fast blow type RS# 270-1013. 2. Change kickback transorbes to two arrays of 600V types. 3. Increase gate drive to 27 Volts from 18. 4. Decrease gate drive resistance to 10 ohms. The first two are trivial changes to accommodate the higher power. I need higher gate drive voltage since the peak primary current may get to about 5000 amps now! If I don't have enough gate drive voltage, the IGBTs may start to back off and dissipate high power. A "bad" thing... I am not too sure about decreasing the gate drive resistance. It help for a fast turn on of the high currents but it also endangers the IGBTs form high speed switching problems with Ccg. I'll probably use my peak current setup to study that one more. Here is a neat picture I took with the coil lighting a mercury vapor bulb. I think they sell these at the hardware store for less the $10. http://hot-streamer.com/temp/P9290027.jpg Cool that the streamers were coming off the glass and were so straight at first. I think I'll get on of these neat bulbs myself! We also cooked all kinds of things like these three CDs taped to the toroid: http://hot-streamer.com/temp/P9290030.jpg So it is still holding together rock solid and the new inductor clears the way for full power 240VAC operation. At 120VAC the coil does not like to breakout well since it seems to have high secondary current but not a lot of voltage. Hopefully, it will hold together at 240VAC which is about 1500 watts of input power! Cheers, Terry Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Mon, 30 Sep 2002 07:42:26 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Mon, 30 Sep 2002 07:34:44 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: Re: OLTC update X-Mailing-List: archive/latest/3451 X-Loop: tesla@pupman.com Original poster: "Jan Wagner by way of Terry Fritz " Hi Terry, > My top priority now is to gear it up for full 240VAC operation. It has > only run in the 1/4 power mode (120VAC) so far and Bill's lab only has 120 > VAC right now due to an "odd" wiring system. The things I need to change are: > > 3. Increase gate drive to 27 Volts from 18. That sounds rather bad, as the absolute maximum rating for the gate voltage is 20V. It seems like the gate oxide can "usually" survive, sometimes, short peaks of 30V to 40V. But I wouldn't really recommend going beyond the specs of the datasheet! :-) If the Miller capacitance (Cres, ~50pF?) really is a problem, IMHO you should rather try to get a beefier igbt driver, or place an additional bipolar buffer stage after the TLP250 opto to get more output sink/source current and thus a more rigid gate signal. > 4. Decrease gate drive resistance to 10 ohms. Ah, ok, you were using 82 Ohms? http://hot-streamer.com/temp/OLTC-IGBTdrive.gif Miller causes I_cg = 2*pi*100kHz * 50pF * 480Vpp = 15mA just as a guesstimate, for each igbt. This charges and discharges the gate-emitter capacitance a bit. I'm not so sure whether the change in gate voltage is significant, though... The current is caused by the primary voltage ringing, regardless of the gate resistance. So a lower gate resistance should AFAIK help here to clean up the gate signal a bit, by sourcing and sinking those 15mA. Probably a spice or aplac simulation would be nice at this point... ;o) cheers, - Jan -- ************************************************* high voltage at http://www.hut.fi/~jwagner/tesla Jan OH2GHR Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Mon, 30 Sep 2002 07:43:37 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Mon, 30 Sep 2002 07:36:43 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: Re: OLTC update X-Mailing-List: archive/latest/3455 X-Loop: tesla@pupman.com Original poster: "Jan Wagner by way of Terry Fritz " > > 4. Decrease gate drive resistance to 10 ohms. > > Ah, ok, you were using 82 Ohms? > http://hot-streamer.com/temp/OLTC-IGBTdrive.gif > > Miller causes > I_cg = 2*pi*100kHz * 50pF * 480Vpp = 15mA > just as a guesstimate, for each igbt. Oops, my apologies! I just forgot the parallel diode in the IGBT, and then the collector-emitter voltage of course never will be 480Vpp during igbt ON state. So please ignore. ;) But less gate resistance should nevertheless help to get a better signal and less noise on the gate. With all the HV RF around... cheers, - Jan -- ************************************************* high voltage at http://www.hut.fi/~jwagner/tesla Jan OH2GHR Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Mon, 30 Sep 2002 21:48:07 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Mon, 30 Sep 2002 21:05:59 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: RE: OLTC update X-Mailing-List: archive/latest/3495 X-Loop: tesla@pupman.com Original poster: "Wall Richard Wayne by way of Terry Fritz " Terry, I agree, this is a fantastic picture. Particularly interesting is the very fine and precise spiraling nature of the small straight streamers. > > http://hot-streamer.com/temp/P9290027.jpg > > Cool that the streamers were coming off the glass and were so straight at > first. I think I'll get on of these neat bulbs myself! RWW --- Richard Wayne Wall --- rwall@ix.netcom.com Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Mon, 30 Sep 2002 21:52:21 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Mon, 30 Sep 2002 21:33:23 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: Re: OLTC update X-Mailing-List: archive/latest/3503 X-Loop: tesla@pupman.com Original poster: "Terry Fritz" Hi Jan, The high gate voltage (27 volts = three 9V batteries) is needed since I am running about 500 peak amps per IGBT. 2.5X their rating :-)) So I need "extra" gate voltage to insure the CE gate stays in saturation. The Ic vs. Vge graph shows to get "really high" current you have to have pretty high gate voltage. Of course, I really should have used 15 IGBTs in retrospect to keep the gate voltage and current per device down. I am not worried about gate failure. I will test a spare IGBT sometime but I bet they are solid to 50 volts. The gate bonds are big and these are copper metalized ICs. They are built for big currents and fast gate switching ;-)) The IGBTs "can" turn on or off an "any" time. The control circuit turns them on and off nicely but the coil is designed to withstand errant triggers too. So I could turn the IGBTs on and turn them off in the middle (peak voltage) of the next cycle or something like that. So to keep the thing reliable, even under fault conditions, it has to take any IGBT timing signal and survive. I clamp the gates with high voltage transorbs now but they are on the "other side" of the gate resistors. Thus, a high dV/dT on the collector might be able to drive the gates high if the resistors are too high of value. Of course, lowering them increases dV/dT too.... The TP250s are no light weights either. One "very bad" signal occurs if you turn the IGBTs off while the primary current is maximum. That give a BIG positive voltage kick right across the IGBTS!! ""7 Joules!!"" stored on a single turn 404nH coil!! BIG dV/dT there!!! I have transorbes on that too but the voltage can jump from say zero to the clamp voltage terribly fast and perhaps drive the gate voltage up with it. I seem to have plenty of room to fiddle With all this so it's not a really big deal but I do want to do it right the first time :-)) I should (according to MicroSim) put small caps across that coil, but then I get HF ringing... This is what I was warned about early on and finally figure out ;-)) Cheers, Terry At 03:41 PM 9/30/2002 +0300, you wrote: >> > 4. Decrease gate drive resistance to 10 ohms. >> >> Ah, ok, you were using 82 Ohms? >> http://hot-streamer.com/temp/OLTC-IGBTdrive.gif >> >> Miller causes >> I_cg = 2*pi*100kHz * 50pF * 480Vpp = 15mA >> just as a guesstimate, for each igbt. > >Oops, my apologies! I just forgot the parallel diode in the IGBT, and >then the collector-emitter voltage of course never will be 480Vpp during >igbt ON state. So please ignore. ;) > >But less gate resistance should nevertheless help to get a better signal >and less noise on the gate. With all the HV RF around... > >cheers, > - Jan > >-- >************************************************* > high voltage at http://www.hut.fi/~jwagner/tesla > Jan OH2GHR > > Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Tue, 1 Oct 2002 08:50:00 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Tue, 01 Oct 2002 08:14:40 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: Re: OLTC update X-Mailing-List: archive/latest/3515 X-Loop: tesla@pupman.com Original poster: "Jan Wagner by way of Terry Fritz " Hi Terry, > The high gate voltage (27 volts = three 9V batteries) is needed since I am > running about 500 peak amps per IGBT. 2.5X their rating :-)) Yeah works as long as max power dissipation at specific junction temperature is not exceeded. Something like 10 x Ic_peak_max possible, AFAIK, but only for a few microseconds. If your igbts survive longer than a few runs that'd be quite promising! ;) Those buggers really seem to get a hard life, 2.5x the rating :-) Well at least it seems they're latch-up free pretty high over ratings, so one less worry... > So I need > "extra" gate voltage to insure the CE gate stays in saturation. The Ic vs. > Vge graph shows to get "really high" current you have to have pretty high > gate voltage. Of course, I really should have used 15 IGBTs in retrospect > to keep the gate voltage and current per device down. > I am not worried about gate failure. I will test a spare IGBT sometime > but I bet they are solid to 50 volts. The gate bonds are big and these > are copper metalized ICs. They are built for big currents and fast gate > switching ;-)) Peak gate current and maximum gate voltage depend on two different things. Using real metallization instead of poly on the gate "just" reduces gate series resistance. The maximum gate voltage is mainly restricted by the gate oxide thickness... http://www.irf.com/technical-info/appnotes/an-936.pdf http://www.fairchildsemi.com/an/AN/AN-9016.pdf (some nice I_c peak calculations there, too...) I've never heared anyone use more than 20V, really. While it seems that typical gate oxide punchthrough voltage _might_ be a stunning 70V..80V for _some_ devices, no datasheets specifically mention that. Probably an unreliably controllable process parameter. I.e. if you get all your current igbts to work at 50V for an extended time, that'd be a small miracle... ;o) Better stack up more IGBTs. That would solve a lot of problems. Maybe there's still room on the back side of the heatsink? :) Anyways, what I get from the is IRG4PC50FD datasheet, as an estimate, is 300A at 12V Vge. Then around 400A at 14V. 500A at 16V? 600A at 18V? Before c-e saturates. Hard to tell as the curves end "too early" and some are missing. Voltages look lower for IRG4PC50WD (again, just an "extend the graph" estimate :-) Have you measured that they really do saturate? And it isn't due to unequal current sharing? > The IGBTs "can" turn on or off an "any" time. The control circuit turns > them on and off nicely but the coil is designed to withstand errant > triggers too. So I could turn the IGBTs on and turn them off in the middle > (peak voltage) of the next cycle or something like that. So to keep the > thing reliable, even under fault conditions, it has to take any IGBT timing > signal and survive. I clamp the gates with high voltage transorbs now but > they are on the "other side" of the gate resistors. Thus, a high dV/dT on > the collector might be able to drive the gates high if the resistors are > too high of value. Of course, lowering them increases dV/dT too.... The > TP250s are no light weights either. Negative gate bias may be helpful there. Negative bias is a good thing in any case. :o) Should be easy with the TP250s too, just one 9V battery more. > One "very bad" signal occurs if you turn the IGBTs off while the primary > current is maximum. That give a BIG positive voltage kick right across the > IGBTS!! ""7 Joules!!"" stored on a single turn 404nH coil!! BIG dV/dT > there!!! I have transorbes on that too but the voltage can jump from say > zero to the clamp voltage terribly fast and perhaps drive the gate voltage > up with it. Yeah even fast transorbs are like >5ns clamping response time so with really huge dV/dt it may not clamp fast enough to prevent Vc-e overvoltage. And then the capacitive coupling to the gate too (again, negative bias helps a bit)... OTOH, you could trade this in with slower igbt turn off (but still use fast turn on). If interrupted (over)current doesn't happen repetetively then just _maybe_ the igbts won't explode. More igbts, anyone? :) cheers, - Jan -- ************************************************* high voltage at http://www.hut.fi/~jwagner/tesla Jan OH2GHR Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Tue, 1 Oct 2002 13:21:39 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Tue, 01 Oct 2002 13:18:10 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: Re: OLTC update X-Mailing-List: archive/latest/3530 X-Loop: tesla@pupman.com Original poster: "Terry Fritz" Hi Jan, Since The gate capacitance and the reverse transfer capacitance form a voltage divider (45pF / (45pF + 3300pF) = .0135 we need a vastly greater dV/dT on the collector to drive the gate high too. Since the output capacitance is 200pF (note these capacitances change with voltage but...) and we have ten IGBTs, the resonating capacitance is 2nF. We now know the frequency is 5.6MHz. Well slow enough for bipolar transorbs to catch. To extend such fun, we also know the theoretical peak voltage of the spike. Assuming no loss, we are transferring 650VDC at 47uF (9.9J) to 2nF... Only 99.6kV ;-)) The dV/dT is 4 x Vp x F = 2.2MV/uS That is a "REAL" dV/dT :o)) With the capacitive voltage divider from above, the gates see about 1350V!! So the question is, why don't they blow right up?!! First, the losses are enormous. Q = L /(C x R) so if the resistance is say 1000 ohms the Q is 0.2. Then you have the secondary, transorbes, and strays eating at it too. But the real key are those transorbs. They smack that pulse like a ton of bricks at about 750 Volts so the gates may see a 10 Volt rise. It is all sort of messy, but really very beautiful how it all works :-)) Apparently, that 10 joules gets eaten up in the CE resistance of the IGBT as it switches since that is a far better looking load to the energy. Only the very first few 10s of nS of the pulse really gets to try to make high voltage. Of course, the coil is "eating" 1200 watts in such a condition but that "should" go to warming the heatsink as opposed to blowing the thing apart. It has all worked so far ;-)) More below... At 01:17 PM 10/1/2002 +0300, you wrote: >Hi Terry, > >> The high gate voltage (27 volts = three 9V batteries) is needed since I am >> running about 500 peak amps per IGBT. 2.5X their rating :-)) > >Yeah works as long as max power dissipation at specific junction >temperature is not exceeded. Something like 10 x Ic_peak_max possible, >AFAIK, but only for a few microseconds. >If your igbts survive longer than a few runs that'd be quite promising! ;) >Those buggers really seem to get a hard life, 2.5x the rating :-) >Well at least it seems they're latch-up free pretty high over ratings, so >one less worry... > I have run the IGBT to 750 amps. That is about the limit where they loose all control of themselves. The gate just can no longer control the current. So I guess I have 50% "headroom" condition as opposed to 250% "over spec" condition :oD Here are some fun scope pics: http://hot-streamer.com/temp/OLTC08-18-08.gif That is turning the IGBTs off at current "peak". Spark gaps don't do that ;-) Note the "scream" it makes as the system wildly tries to dissipate the stored energy (no secondary). http://hot-streamer.com/temp/OLTC08-21-02.gif This is just a little low power spike. Note how slow it really is: http://hot-streamer.com/temp/OLTC08-21-03.gif Here it is being hit by a transorb: http://hot-streamer.com/temp/OLTC08-21-04.gif http://hot-streamer.com/temp/OLTC08-21-05.gif The transorb is highly effective as long as it does not get blown away ;-) Here is an Icollector graph for a single IGBT that the data sheet does not have ;-) http://hot-streamer.com/temp/OLTC08-30-02.gif At about 750 amps it just starts to flat top. I could easily play with that point if I did not let the IGBT get too hot. Never blew the IGBT even as the current tore it out of saturation (Vce about 500 volts too...). They are REALLY tough ;-) >> So I need >> "extra" gate voltage to insure the CE gate stays in saturation. The Ic vs. >> Vge graph shows to get "really high" current you have to have pretty high >> gate voltage. Of course, I really should have used 15 IGBTs in retrospect >> to keep the gate voltage and current per device down. >> I am not worried about gate failure. I will test a spare IGBT sometime >> but I bet they are solid to 50 volts. The gate bonds are big and these >> are copper metalized ICs. They are built for big currents and fast gate >> switching ;-)) > >Peak gate current and maximum gate voltage depend on two different things. >Using real metallization instead of poly on the gate "just" reduces gate >series resistance. The maximum gate voltage is mainly restricted by the gate >oxide thickness... > http://www.irf.com/technical-info/appnotes/an-936.pdf > http://www.fairchildsemi.com/an/AN/AN-9016.pdf > (some nice I_c peak calculations there, too...) > >I've never heared anyone use more than 20V, really. While it seems that >typical gate oxide punchthrough voltage _might_ be a stunning 70V..80V for >_some_ devices, no datasheets specifically mention that. Probably >an unreliably controllable process parameter. >I.e. if you get all your current igbts to work at 50V for an extended >time, that'd be a small miracle... ;o) > >Better stack up more IGBTs. That would solve a lot of problems. >Maybe there's still room on the back side of the heatsink? :) Next time ;-) > >Anyways, what I get from the is IRG4PC50FD datasheet, as an estimate, is >300A at 12V Vge. Then around 400A at 14V. 500A at 16V? 600A at 18V? >Before c-e saturates. Hard to tell as the curves end "too early" and some >are missing. Voltages look lower for IRG4PC50WD (again, just >an "extend the graph" estimate :-) Have to remember that the batteries wear down too! If they are at 7 volts, then I have 21 volts still very safe. With two batteries I have only 14 volts and hot IGBTs! > >Have you measured that they really do saturate? 750 amps. I don't think more gate voltages matters after that... >And it isn't due to unequal current sharing? No, too much current, not enough IGBT active region. The little IGBT just can't control any more current with its gate structure doping regions and all. BTW - Even though I am pushing enormous currents, the total power dissipation is only 5 - 10 watts (low duty cycle). Thus the IGBTs run very cool. That really helps :-)) But the pulse may superheat the wire bonds, shatter the die (thermal shock), or generally tear the IGBT apart. Hopefully, relatively long term failure mechanisms... Even the magnetic forces could do damage. > >> The IGBTs "can" turn on or off an "any" time. The control circuit turns >> them on and off nicely but the coil is designed to withstand errant >> triggers too. So I could turn the IGBTs on and turn them off in the middle >> (peak voltage) of the next cycle or something like that. So to keep the >> thing reliable, even under fault conditions, it has to take any IGBT timing >> signal and survive. I clamp the gates with high voltage transorbs now but >> they are on the "other side" of the gate resistors. Thus, a high dV/dT on >> the collector might be able to drive the gates high if the resistors are >> too high of value. Of course, lowering them increases dV/dT too.... The >> TP250s are no light weights either. > >Negative gate bias may be helpful there. Negative bias is a good thing in >any case. :o) Should be easy with the TP250s too, just one 9V battery >more. > >> One "very bad" signal occurs if you turn the IGBTs off while the primary >> current is maximum. That give a BIG positive voltage kick right across the >> IGBTS!! ""7 Joules!!"" stored on a single turn 404nH coil!! BIG dV/dT >> there!!! I have transorbes on that too but the voltage can jump from say >> zero to the clamp voltage terribly fast and perhaps drive the gate voltage >> up with it. > >Yeah even fast transorbs are like >5ns clamping response time so with >really huge dV/dt it may not clamp fast enough to prevent Vc-e >overvoltage. And then the capacitive coupling to the gate too (again, >negative bias helps a bit)... > >OTOH, you could trade this in with slower igbt turn off (but still use >fast turn on). If interrupted (over)current doesn't happen repetetively >then just _maybe_ the igbts won't explode. More igbts, anyone? :) Next time, more IGBTs and more TP250's so I can drive a bit more gate current. But I am still fairly safe for the "first" OLTC try ;-)) But if the IGBTs do fail, I should know right away :o))) Probably at about 4,000,000VA!!!! BTW - I just got my TEK P5205 High-voltage differential probe :-)) So gate and CE voltages will be real easy to see now!! Differntial two probe measurements of high speed things just don't go well and digital scopes. Really needs a real differential probe. Cheers, Terry > >cheers, > - Jan > >-- >************************************************* > high voltage at http://www.hut.fi/~jwagner/tesla > Jan OH2GHR > Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Tue, 1 Oct 2002 21:02:35 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Tue, 01 Oct 2002 20:53:07 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: RE: OLTC update X-Mailing-List: archive/latest/3547 X-Loop: tesla@pupman.com Original poster: "Wall Richard Wayne by way of Terry Fritz " Terry, Not only are the streamers off the bulb straight and spiraling, but one side is spiraling opposite to the other side. Looks like the left side streamers are clock wise and the right side are counter clock wise off the bulb. This definitely has implications as to the flow of electrical energy in to - out of streamers on opposite sides of the bulb. > http://hot-streamer.com/temp/P9290027.jpg > > Cool that the streamers were coming off the glass and were so straight at > first. I think I'll get on of these neat bulbs myself! RWW Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Tue, 1 Oct 2002 21:00:18 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Tue, 01 Oct 2002 20:55:52 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: RE: OLTC update X-Mailing-List: archive/latest/3543 X-Loop: tesla@pupman.com Original poster: "Terry Fritz" Hi Richard, I should point out that the picture has sort of a long exposure (not sure how long but about 1 second). So the streamers may not have been occuring at the same time. I should try and set this up again... I would think any coil would do this same thing. Cheers, Terry At 09:16 PM 10/1/2002 -0400, you wrote: >Terry, > >Not only are the streamers off the bulb straight and spiraling, but one >side is spiraling opposite to the other side. Looks like the left side >streamers are clock wise and the right side are counter clock wise off the >bulb. This definitely has implications as to the flow of electrical energy >in to - out of streamers on opposite sides of the bulb. > >> http://hot-streamer.com/temp/P9290027.jpg >> >> Cool that the streamers were coming off the glass and were so straight at >> first. I think I'll get on of these neat bulbs myself! > >RWW > Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Wed, 2 Oct 2002 00:11:25 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Wed, 02 Oct 2002 00:03:46 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: Re: OLTC update X-Mailing-List: archive/latest/3551 X-Loop: tesla@pupman.com Original poster: "Barton B. Anderson by way of Terry Fritz " Hi Terry, Regardless of exposure, it appears "all" on the left spiral in one direction while the right in the other direction. It is quite interesting and a good observation which I had overlooked. It appears "not" random. Bart Tesla list wrote: > Original poster: "Terry Fritz" > > Hi Richard, > > I should point out that the picture has sort of a long exposure (not sure > how long but about 1 second). So the streamers may not have been occuring > at the same time. I should try and set this up again... I would think any > coil would do this same thing. > > Cheers, > > Terry > > At 09:16 PM 10/1/2002 -0400, you wrote: > >Terry, > > > >Not only are the streamers off the bulb straight and spiraling, but one > >side is spiraling opposite to the other side. Looks like the left side > >streamers are clock wise and the right side are counter clock wise off the > >bulb. This definitely has implications as to the flow of electrical energy > >in to - out of streamers on opposite sides of the bulb. > > > >> http://hot-streamer.com/temp/P9290027.jpg > >> > >> Cool that the streamers were coming off the glass and were so straight at > >> first. I think I'll get on of these neat bulbs myself! > > > >RWW > > Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Wed, 2 Oct 2002 00:17:25 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Wed, 02 Oct 2002 00:15:47 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: Re: OLTC update X-Mailing-List: archive/latest/3552 X-Loop: tesla@pupman.com Original poster: "Terry Fritz" Hi, Ok, I guess I ain't see'n it ;-)) Perhaps the old eyes and late night... But them bulbs are pretty cheap at $5 to $10 bucks so anyone can check this stuff out. It is that old cork screw streamers thing, that was never answered... I was way too busy playing with the camera, controls, and local fellows not getting zapped to notice much details, but it sounds like cool stuff was goin on there ;-)) Cheers, Terry At 10:26 PM 10/1/2002 -0700, you wrote: >Hi Terry, > >Regardless of exposure, it appears "all" on the left spiral in one direction >while the right in the other direction. It is quite interesting and a good >observation which I had overlooked. It appears "not" random. > >Bart > >Tesla list wrote: > Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Wed, 2 Oct 2002 08:31:31 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Wed, 02 Oct 2002 08:29:02 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: Re: OLTC update X-Mailing-List: archive/latest/3559 X-Loop: tesla@pupman.com Original poster: "sundog by way of Terry Fritz " Hmm. That's interesting Terry! I've never seen that effect on my VTTC's. Even with two breakout points, the streamers all spiraled counter-clockwise from the bottom up. Wonder if a bi-polar coil will spiral in different directions..... Shad At 02:15 AM 10/2/02, you wrote: >Original poster: "Terry Fritz" > >Hi, > >Ok, I guess I ain't see'n it ;-)) Perhaps the old eyes and late night... >But them bulbs are pretty cheap at $5 to $10 bucks so anyone can check this >stuff out. It is that old cork screw streamers thing, that was never >answered... > >I was way too busy playing with the camera, controls, and local fellows not >getting zapped to notice much details, but it sounds like cool stuff was >goin on there ;-)) > >Cheers, > > Terry > >At 10:26 PM 10/1/2002 -0700, you wrote: > >Hi Terry, > > > >Regardless of exposure, it appears "all" on the left spiral in one direction > >while the right in the other direction. It is quite interesting and a good > >observation which I had overlooked. It appears "not" random. > > > >Bart > > > >Tesla list wrote: > > ----------------------------------------------------------------------- Shad (Sundog) G-5 #1203 "Ever stop to think, and forget to start again?" ----------------------------------------------------------------------- Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Wed, 2 Oct 2002 19:12:36 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Wed, 02 Oct 2002 19:01:22 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: Re: OLTC update X-Mailing-List: archive/latest/3577 X-Loop: tesla@pupman.com Original poster: "teri mckenney by way of Terry Fritz " Hey Terry, I've done this with small refrigerator bulbs (25watts?) on up to the bigger mercury vapor bulbs.I have a 1,000 watt one I've thought about using but I don't want to mess it up:o). One of the neatest things I've fried on the coil is some long stemmed roses sitting straight up in a skinny vase.The streamers come off the rose pedals. B.Mck. > Here is a neat picture I took with the coil lighting a mercury vapor bulb. > I think they sell these at the hardware store for less the $10. > > http://hot-streamer.com/temp/P9290027.jpg > > Cool that the streamers were coming off the glass and were so straight at > first. I think I'll get on of these neat bulbs myself! > > We also cooked all kinds of things like these three CDs taped to the toroid: > > http://hot-streamer.com/temp/P9290030.jpg > > Cheers, > > Terry > > > > > Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Thu, 3 Oct 2002 18:26:58 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Thu, 03 Oct 2002 18:22:45 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: Re: OLTC update X-Mailing-List: archive/latest/3653 X-Loop: tesla@pupman.com Original poster: "marc metlicka by way of Terry Fritz " Hi Terry, list This type of a set-up is what i was using when i was trying to find the "breakout threshold" voltage for the TSSP a while back Maybe you remember my comments on the project discussion groups mail? Anyway, I found that even though the different coils or configs caused wildly different needs from the line PSU, there seemed to be a steady topload voltage that it took to breach the glass of the 1000 watt incandescent i was using? With each different set-up, or coil, the plasma within the glass envelope would vary intensely, but it seemed to me that the point where the discharge would breakthrough the glass was some kind of constant? This didn't seem effected by frequency, It didn't seem effected by any outer field density from different sized coil\toploads, but each different set-up or coil would need a different input voltage from the variac to get ac breakthrough discharge (always the same PSU) This is why i'm thinking that the voltage to get breakout from the glass might be even. Maybe now that a topV probe has been found, this could be investigated? I thought i would mention it on the list in case anyone would like to pick up where i left off in the spring? Take care Marc M. > > > Here is a neat picture I took with the coil lighting a mercury vapor bulb. > > I think they sell these at the hardware store for less the $10. > > > > http://hot-streamer.com/temp/P9290027.jpg > > > > Cool that the streamers were coming off the glass and were so straight at > > first. I think I'll get on of these neat bulbs myself! > > > > We also cooked all kinds of things like these three CDs taped to the > toroid: > > > > http://hot-streamer.com/temp/P9290030.jpg > > > > Cheers, > > > > Terry > > > > > > > > > > Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Fri, 4 Oct 2002 18:11:59 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Fri, 04 Oct 2002 17:28:02 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: Re: OLTC update X-Mailing-List: archive/latest/3702 X-Loop: tesla@pupman.com Original poster: "marc metlicka by way of Terry Fritz " Original poster: "marc metlicka by way of Terry Fritz " Hi Terry, list This type of a set-up is what i was using when i was trying to find the "breakout threshold" voltage for the TSSP a while back Maybe you remember my comments on the project discussion groups mail? Anyway, I found that even though the different coils or configs caused wildly different needs from the line PSU, there seemed to be a steady topload voltage that it took to breach the glass of the 1000 watt incandescent i was using? With each different set-up, or coil, the plasma within the glass envelope would vary intensely, but it seemed to me that the point where the discharge would breakthrough the glass was some kind of constant? This didn't seem effected by frequency, It didn't seem effected by any outer field density from different sized coil\toploads, but each different set-up or coil would need a different input voltage from the variac to get ac breakthrough discharge (always the same PSU) This is why i'm thinking that the voltage to get breakout from the glass might be even. Maybe now that a topV probe has been found, this could be investigated? I thought i would mention it on the list in case anyone would like to pick up where i left off in the spring? Take care Marc M. > > > Here is a neat picture I took with the coil lighting a mercury vapor bulb. > > I think they sell these at the hardware store for less the $10. > > > > http://hot-streamer.com/temp/P9290027.jpg > > > > Cool that the streamers were coming off the glass and were so straight at > > first. I think I'll get on of these neat bulbs myself! > > > > We also cooked all kinds of things like these three CDs taped to the > toroid: > > > > http://hot-streamer.com/temp/P9290030.jpg > > > > Cheers, > > > > Terry > > > > > > > > > > Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Sat, 21 Sep 2002 23:26:46 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Sat, 21 Sep 2002 23:23:40 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: OLTC update 240BPS inductor X-Mailing-List: archive/latest/3023 X-Loop: tesla@pupman.com Original poster: "Terry Fritz" Hi All, As it turns out, there just is not anyway to wind a 34mH air inductor with #18 wire without having to use about 600 feet of wire at about 4 ohms of resistance. I'll spare you all the torturous calculations... http://hot-streamer.com/temp/OLTC09-21-01.gif At about 6.3 amps RMS input, 4 ohms is (I^2R) 160 watts of R heating just in the inductor! Worse yet, it tends to spoil the resonant charging. So I went back to a split core toroid. Happily it turns out to be even lighter than 600 feet of # 18 :-)) Going from 150mH at 4 amps peak to 34mH at 10 amps peak makes a ton of difference!! Weighing in at 3 pounds 5 ounces, May new 34mH inductor can go to 10 amps without saturation. It also only has a DC resistance of 0.856 ohm or 34 watts of heat. Better still, it is now 240VAC ready :-))): http://hot-streamer.com/temp/OLTC09-21-04.jpg Notice those red hands from winding 300 turns on this puppy ;-)) Sawing the core was not easy either! I sawed it twice to get a nice big 1/4 inch gap. Even though these cores are tape wound, sawing them was not a big deal and they stay together pretty well. Even though I was just wildly guessing at core size and all I got lucky and it worked out just right: http://hot-streamer.com/temp/OLTC09-21-02.gif http://hot-streamer.com/temp/OLTC09-21-03.gif I goofed up on that Req = SQRT(Rdc^2 + Xl^2) stuff... So the core is really 36.3mH. Not a big deal and I decide to wait till I could actually run it to do any fine tuning. The line input current looks like this: http://hot-streamer.com/temp/OLTC09-21-04.gif "Funny" but not to bad at all. Drawing 6.31amps at 240VAC in gives a system input power of around 1500 watts. Firing voltage is 580 volts and the peak primary current is a toasty 5732 amps ;-)) That's 573 amps/IGBT! Probably should have used 15 IGBTs... It will be ok as long as I don't run it too long to heat them up. So running at 240BPS with this much "easier" inductor seems like a great thing! I'll see if I can get some real testing done tomorrow. Many thank to Richie ;-)) Cheers, Terry Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Thu, 19 Sep 2002 18:57:20 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Thu, 19 Sep 2002 18:37:17 -0600 (MDT) From: "Tesla list" To: tesla@poodle.pupman.com.rmpg.org Subject: RE: OLTC update (fwd) X-Mailing-List: archive/latest/2871 X-Loop: tesla@pupman.com Original poster: Tesla List Moderator ---------- Forwarded message ---------- Date: Thu, 19 Sep 2002 02:43:57 +0000 From: Laurence Davis To: tesla@pupman.com Subject: RE: OLTC update Terry, this seems like it would take the fun out of it, but could a circuit be designed to automatically tune the oltc coil? perhaps by monitoring current draw on the primary and varying within a range of dwell time and searching for max current? larry. _________________________________________________________________ Chat with friends online, try MSN Messenger: http://messenger.msn.com Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Wed, 28 Aug 2002 20:24:43 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Wed, 28 Aug 2002 20:19:09 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: OLTC update - A problem! X-Mailing-List: archive/latest/1683 X-Loop: tesla@pupman.com Original poster: "Terry Fritz" Hi All, I retuned the coupling and all http://hot-streamer.com/temp/OLTC08-28-08.gif on the OLTC and the performance was better but still not as I had hoped. I think I know why now. Using the output impedance calculation method at: http://hot-streamer.com/TeslaCoils/Misc/impedance/impedance.html I came up with an output impedance for my coil of 2,044,989 ohms!! That is really high! My big coil is only 26500 ohms. So I think the coil's output impedance is too high to fry nitrogen the way we would like it too. Output impedance is governed by the Lsec and Csec ratio. So I think I need a smaller secondary L and a top terminal the size of a cow or something... I'll have to work on this... I was worried about this, but I didn't think I would make it this far so soon :o)) I suspect this problem plagues most low frequency coils. I was modeling the coil to run into a 220KOhm + 2pF streamer load which has a magnitude of 2,191,278 ohms so it "should" have worked from that point of view. Source and load "should" have been closely matched. But it looks like there are a few unknowns still out there ;-) With 286 watts in I should be able to get streamers of 28 inches according to John's formula. Much more considering I am not burning power in a spark gap. But either the low frequency (I note that I am at the frequency of Greg Leyh's Electrum which seems to come in a little low for streamer length given the input power) or the impedance thing is causing a problem. Probably time to get out them fiber-optic probes ;-)) In other news... I designed in IGBT current tester. Here is the simple diagram: http://hot-streamer.com/temp/OLTC08-28-06.gif Here is the messy one: http://hot-streamer.com/temp/OLTC08-28-07.gif It is basically a copy of a single section of the coil. I played the values to get an almost perfect matching current waveform to the real one but I can push 600 peak amps here on a single IGBT (1200 amps with a slight modification!). I will probably use the coil's drive modules to run it but making another drive circuit is pretty easy too. With this tester I can run the IGBTs until they break and determine how hard I can push them. apparently nobody knows how hard IGBTs can be pushed in such case. Be interesting to see :-)) The impedance problem is the first real "obnoxious" problem with the OLTC. But it is not a mater if an OLTC works now but rather how to perfect it ;-)) BTW - For 50 Hz UK operation. the charging inductor needs to be: 50 = 1 / (2 x pi x SQRT (47e-6 x L)) Where L = 215.6mH Big ~6 to 10 pound split core (E-core may be better)) that does not saturate given the current. I guess it could be designed for a saturable reactor if one were really good at that stuff... You need to watch that the peak value of the primary voltage does not go too high with the longer charging time and the line voltage you have over there. I can't think of anything else that would be affected. I am not sure my IGBTs can take 240VAC yet until I do the destructive testing... The IGBTs and stuff will be here Friday so I can do that this weekend. I should point out that this OLTC stuff is all brand new bleeding edge stuff and I am using a ton and a half of computer models and extravagant test equipment to get it to work. The goal is to make it very simple and easy, but right now the guarantees are zero for those that wish to try it themselves. Things have gone extremely well, but if you try it and have trouble right now, just don't blame me :o))) Cheers, Terry Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Wed, 28 Aug 2002 21:04:27 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Wed, 28 Aug 2002 21:00:15 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: Re: OLTC update - A problem! X-Mailing-List: archive/latest/1688 X-Loop: tesla@pupman.com Original poster: "jimmy hynes by way of Terry Fritz " impedance of the secondary shouldn't have any effect on the output efficiency. the impedance would have an effect on the amount of power for a given voltage, but in this case the voltage driving it rises with the impedance. for a fixed k, the voltage driving the secondary because it sees more turns. besides where would the power go? with a ss spark gap you should be able to do better. i cant see how impedance would matter, but i could be wrong. Tesla list wrote: > > Original poster: "Terry Fritz" > > Hi All, > > I retuned the coupling and all > > http://hot-streamer.com/temp/OLTC08-28-08.gif > > on the OLTC and the performance was better but still not as I had hoped. I > think I know why now. > > Using the output impedance calculation method at: > > http://hot-streamer.com/TeslaCoils/Misc/impedance/impedance.html > > I came up with an output impedance for my coil of 2,044,989 ohms!! That is > really high! My big coil is only 26500 ohms. So I think the coil's output > impedance is too high to fry nitrogen the way we would like it too. > > Output impedance is governed by the Lsec and Csec ratio. So I think I need > a smaller secondary L and a top terminal the size of a cow or something... > I'll have to work on this... I was worried about this, but I didn't think > I would make it this far so soon :o))! I suspect this problem plagues most > low frequency coils. I was modeling the coil to run into a 220KOhm + 2pF > streamer load which has a magnitude of 2,191,278 ohms so it "should" have > worked from that point of view. Source and load "should" have been closely > matched. But it looks like there are a few unknowns still out there ;-) > With 286 watts in I should be able to get streamers of 28 inches according > to John's formula. Much more considering I am not burning power in a spark > gap. But either the low frequency (I note that I am at the frequency of > Greg Leyh's Electrum which seems to come in a little low for streamer > length given the input power) or the impedance thing is causing a problem. > Probably time to get out them fiber-optic probes ;-)) > > > In other news... I designed in IGBT current tester. Here is the simple > diagram: > > http://hot-streamer.com/temp/OLTC08-28-06.gif > > Here is the messy one: > > http://hot-streamer.com! /temp/OLTC08-28-07.gif > > It is basically a copy of a singl! e section of the coil. I played the > values to get an almost perfect matching current waveform to the real one > but I can push 600 peak amps here on a single IGBT (1200 amps with a slight > modification!). I will probably use the coil's drive modules to run it but > making another drive circuit is pretty easy too. With this tester I can > run the IGBTs until they break and determine how hard I can push them. > apparently nobody knows how hard IGBTs can be pushed in such case. Be > interesting to see :-)) > > The impedance problem is the first real "obnoxious" problem with the OLTC. > But it is not a mater if an OLTC works now but rather how to perfect it ;-)) > > > BTW - For 50 Hz UK operation. the charging inductor needs to be: > > 50 = 1 / (2 x pi x SQRT (47e-6 x L)) Where L = 215.6mH Big ~6 to 10 > pound split core (E-core may be better)) that does not saturate given the > current. I guess it could be designed for a saturable reactor if one were > ! really good at that stuff... > > You need to watch that the peak value of the primary voltage does not go > too high with the longer charging time and the line voltage you have over > there. I can't think of anything else that would be affected. I am not > sure my IGBTs can take 240VAC yet until I do the destructive testing... > The IGBTs and stuff will be here Friday so I can do that this weekend. > > > I should point out that this OLTC stuff is all brand new bleeding edge > stuff and I am using a ton and a half of computer models and extravagant > test equipment to get it to work. The goal is to make it very simple and > easy, but right now the guarantees are zero for those that wish to try it > themselves. Things have gone extremely well, but if you try it and have > trouble right now, just don't blame me :o))) > > Cheers, > > Terry > > JImmy Do You Yahoo!? Yahoo! Finance - Get real-time stock quotes Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Wed, 28 Aug 2002 21:39:33 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Wed, 28 Aug 2002 21:34:05 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: Re: OLTC update - A problem! X-Mailing-List: archive/latest/1689 X-Loop: tesla@pupman.com Original poster: "Terry Fritz" Hi Jimmy, It is really weird, I can take the secondary off and run the coil. The energies are much the same, but without a secondary, where in the world does the power go?! I guess I should run the coil at full power to "find out", but I think the answer would be "unpleasant" :-)) My guess is that the IGBTs will absorb the power if nothing else does. In a conventional coil that is run without a secondary in place, the spark gap gets much brighter, hotter, and louder. I suspect that is still true in the case of the IGBT gap, but the results are "badder". If a very low loss primary system "has" to dissipate 500 watts of power, my guess is that the IGBTs will step forward and take it. there is still much to ponder in all this... Cheers, Terry >At 07:55 PM 8/28/2002 -0700, you wrote: > > > >impedance of the secondary shouldn't have any effect on the output >efficiency. the impedance would have an effect on the amount of power for a >given voltage, but in this case the voltage driving it rises with the >impedance. for a fixed k, the voltage driving the secondary because it sees >more turns. besides where would the power go? with a ss spark gap you should >be able to do better. i cant see how impedance would matter, but i could be >wrong. > Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Wed, 28 Aug 2002 22:40:02 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Wed, 28 Aug 2002 22:31:04 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: Re: OLTC update - A problem! X-Mailing-List: archive/latest/1693 X-Loop: tesla@pupman.com Original poster: "Malcolm Watts by way of Terry Fritz " Hi Terry, On 28 Aug 2002, at 20:19, Tesla list wrote: > Original poster: "Terry Fritz" > > Hi All, > > I retuned the coupling and all > > http://hot-streamer.com/temp/OLTC08-28-08.gif > > on the OLTC and the performance was better but still not as I had hoped. I > think I know why now. > > Using the output impedance calculation method at: > > http://hot-streamer.com/TeslaCoils/Misc/impedance/impedance.html > > I came up with an output impedance for my coil of 2,044,989 ohms!! That is > really high! My big coil is only 26500 ohms. So I think the coil's output > impedance is too high to fry nitrogen the way we would like it too. I think that consideration should only apply if there is no topload. Even then, the coil creates something of a topload all by itself. I am betting from what I've seen of the secondary oscillograms that the secondary Q is rather low. I'm also betting that based on the amount of wire crammed into such a small volume. Have you yet measured/calculated Qs? Perhaps I should stop being lazy and do it myself. > Output impedance is governed by the Lsec and Csec ratio. So I think I need > a smaller secondary L and a top terminal the size of a cow or something... > I'll have to work on this... I was worried about this, but I didn't think > I would make it this far so soon :o)) I suspect this problem plagues most > low frequency coils. I was modeling the coil to run into a 220KOhm + 2pF > streamer load which has a magnitude of 2,191,278 ohms so it "should" have > worked from that point of view. Source and load "should" have been closely > matched. But it looks like there are a few unknowns still out there ;-) > With 286 watts in I should be able to get streamers of 28 inches according > to John's formula. Much more considering I am not burning power in a spark > gap. But either the low frequency (I note that I am at the frequency of > Greg Leyh's Electrum which seems to come in a little low for streamer > length given the input power) or the impedance thing is causing a problem. > Probably time to get out them fiber-optic probes ;-)) I think you are running into conflicts between losses and available energy. For example, running a low L coil with a humungous topload is going to require a bundle of energy to get to a decent voltage. Generally, there are scaling factors at work such as size being proportional to required energy and being inversely proportional to losses. Sorry for the handwaving. Again I'mm too lazy to go through the details. > > In other news... I designed in IGBT current tester. Here is the simple > diagram: > > http://hot-streamer.com/temp/OLTC08-28-06.gif > > Here is the messy one: > > http://hot-streamer.com/temp/OLTC08-28-07.gif > > It is basically a copy of a single section of the coil. I played the > values to get an almost perfect matching current waveform to the real one > but I can push 600 peak amps here on a single IGBT (1200 amps with a slight > modification!). I will probably use the coil's drive modules to run it but > making another drive circuit is pretty easy too. With this tester I can > run the IGBTs until they break and determine how hard I can push them. > apparently nobody knows how hard IGBTs can be pushed in such case. Be > interesting to see :-)) > > The impedance problem is the first real "obnoxious" problem with the OLTC. > But it is not a mater if an OLTC works now but rather how to perfect it ;-)) I didn't doubt it would work to some degree. I ran such a coil at considerably lower voltages using a MOSFET gap years ago. But that was never going to be a match for a system running high primary voltages. Regards, Malcolm > BTW - For 50 Hz UK operation. the charging inductor needs to be: > > 50 = 1 / (2 x pi x SQRT (47e-6 x L)) Where L = 215.6mH Big ~6 to 10 > pound split core (E-core may be better)) that does not saturate given the > current. I guess it could be designed for a saturable reactor if one were > really good at that stuff... > > You need to watch that the peak value of the primary voltage does not go > too high with the longer charging time and the line voltage you have over > there. I can't think of anything else that would be affected. I am not > sure my IGBTs can take 240VAC yet until I do the destructive testing... > The IGBTs and stuff will be here Friday so I can do that this weekend. > > > I should point out that this OLTC stuff is all brand new bleeding edge > stuff and I am using a ton and a half of computer models and extravagant > test equipment to get it to work. The goal is to make it very simple and > easy, but right now the guarantees are zero for those that wish to try it > themselves. Things have gone extremely well, but if you try it and have > trouble right now, just don't blame me :o))) > > Cheers, > > Terry > > > > > Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Wed, 28 Aug 2002 22:46:46 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Wed, 28 Aug 2002 22:42:23 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: Re: OLTC update - A problem! X-Mailing-List: archive/latest/1694 X-Loop: tesla@pupman.com Original poster: "jimmy hynes by way of Terry Fritz " with perfect tuning all the energy should go to the secondary, no matter what the impedance is. you shouldnt get smaller streamers with the same input power and less loss in the gap. if you run the coil without the secondary the energy could go back into charging up the caps, or into the voltage suppression for the igbts. you could make a circuit that would only quench the gap when the reverse recovery diodes are conducting, that way you dont lose any energy. Tesla list > > wrote: > Original poster: "Terry Fritz" > > Hi Jimmy, > > It is really weird, I can take the secondary off and run the coil. The > energies are much the same, but without a secondary, where in the world > does the power go?! > > I guess I should run the coil at full power to "find out", but I think the > answer would be "unpleasant" :-)) My guess is that the IGBTs will absorb > the power if nothing else does. In a conventional coil that is run without > a secondary in place, the spark gap gets much brighter, hotter, and louder. > I suspect that is still true in the case of the IGBT gap, but the results > are "badder". If a very low loss primary system "has" to dissipate 500 > watts of power, my guess is that the IGBTs will step forward and take it. > > there is still much to ponder in all this... > > Cheers, > > Terry > > > > > > >At 07:55 PM 8/28/2! 002 -0700, you wrote: > > > > > > > >impedance of the secondary shouldn't have any effect on the output > >efficiency. the impedance would have an effect on the amount of power for a > >given voltage, but in this case the voltage driving it rises with the > >impedance. for a fixed k, the voltage driving the secondary because it sees > >more turns. besides where would the power go? with a ss spark gap you should > >be able to do better. i cant see how impedance would matter, but i could be > >wrong. > > > > > > > > > > JImmy > Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Thu, 29 Aug 2002 08:09:49 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Thu, 29 Aug 2002 08:02:39 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: Re: OLTC update - A problem! X-Mailing-List: archive/latest/1699 X-Loop: tesla@pupman.com Original poster: "by way of Terry Fritz " In a message dated 8/28/02 10:24:06 PM Eastern Daylight Time, tesla@pupman.com writes: > > With 286 watts in I should be able to get streamers of 28 inches according > to John's formula. Much more considering I am not burning power in a spark > gap. But either the low frequency (I note that I am at the frequency of > Greg Leyh's Electrum which seems to come in a little low for streamer > length given the input power) Terry, Congratulations on your results so far. Regarding Greg's Electrum coil, I seem to remember that it gave about the same spark length, as the break-rate was increased within a certain range. Near the low end of the break-rate range, the coil was quite efficient. I think Greg said the coil gave almost the full spark length of 40 to 50 feet, at 110 bps or so. As he raised the breakrate, the sparks became bushier and fuller, but not much longer. I think it drew 40kW at 110 bps or so, and gave maybe 38 foot sparks. This easily surpasses what my equation predicts. This information is not as Greg's website, and I may not have it 100% accurate, because I gathered it from data in his various emails, but I think it's close, and if I'm correct, it suggests that Greg's coil is capable of very high efficiency at the lower break-rates. Maybe Greg will comment further. John Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Thu, 29 Aug 2002 13:53:14 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Thu, 29 Aug 2002 13:43:05 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: Re: OLTC update - A problem! X-Mailing-List: archive/latest/1710 X-Loop: tesla@pupman.com Original poster: "Mazzilli Vladimiro by way of Terry Fritz " Tesla list wrote: > Original poster: "by way of Terry Fritz " > > In a message dated 8/28/02 10:24:06 PM Eastern Daylight Time, tesla@pupman.com > writes: > > > > > With 286 watts in I should be able to get streamers of 28 inches according > > to John's formula. Much more considering I am not burning power in a spark > > gap. But either the low frequency (I note that I am at the frequency of > > Greg Leyh's Electrum which seems to come in a little low for streamer > > length given the input power) Terry, where is John's formula? Probably I have it in some paper, but I'm not able to find it. Cheers Vladi > > > Terry, > > Congratulations on your results so far. Regarding Greg's Electrum > coil, I seem to remember that it gave about the same spark length, > as the break-rate was increased within a certain range. Near the > low end of the break-rate range, the coil was quite efficient. I think > Greg said the coil gave almost the full spark length of 40 to 50 feet, > at 110 bps or so. As he raised the breakrate, the sparks became > bushier and fuller, but not much longer. I think it drew 40kW at > 110 bps or so, and gave maybe 38 foot sparks. This easily > surpasses what my equation predicts. This information is not > as Greg's website, and I may not have it 100% accurate, because > I gathered it from data in his various emails, but I think it's > close, and if I'm correct, it suggests that Greg's coil is capable > of very high efficiency at the lower break-rates. Maybe Greg > will comment further. > > John Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Thu, 29 Aug 2002 13:53:10 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Thu, 29 Aug 2002 13:45:18 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: Re: OLTC update - A problem! X-Mailing-List: archive/latest/1711 X-Loop: tesla@pupman.com Original poster: "Terry Fritz" Hi, John's formula is at the bottom of this page: http://hometown.aol.com/futuret/page5.html It is: Ques: How long will my sparks be for a given input power? Ans: In a well designed TC, the spark length will follow the formula: spark length (inches) = 1.7*sqrt input power (wallplug watts) Cheers, Terry At 05:10 PM 8/29/2002 +0200, you wrote: > > >Tesla list wrote: > >> Original poster: "by way of Terry Fritz " > >> >> In a message dated 8/28/02 10:24:06 PM Eastern Daylight Time, >tesla@pupman.com >> writes: >> >> > >> > With 286 watts in I should be able to get streamers of 28 inches according >> > to John's formula. Much more considering I am not burning power in a spark >> > gap. But either the low frequency (I note that I am at the frequency of >> > Greg Leyh's Electrum which seems to come in a little low for streamer >> > length given the input power) > >Terry, where is John's formula? Probably I have it in some paper, but I'm >not able >to find it. > >Cheers > >Vladi > >> >> >> Terry, >> >> Congratulations on your results so far. Regarding Greg's Electrum >> coil, I seem to remember that it gave about the same spark length, >> as the break-rate was increased within a certain range. Near the >> low end of the break-rate range, the coil was quite efficient. I think >> Greg said the coil gave almost the full spark length of 40 to 50 feet, >> at 110 bps or so. As he raised the breakrate, the sparks became >> bushier and fuller, but not much longer. I think it drew 40kW at >> 110 bps or so, and gave maybe 38 foot sparks. This easily >> surpasses what my equation predicts. This information is not >> as Greg's website, and I may not have it 100% accurate, because >> I gathered it from data in his various emails, but I think it's >> close, and if I'm correct, it suggests that Greg's coil is capable >> of very high efficiency at the lower break-rates. Maybe Greg >> will comment further. >> >> John > Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Thu, 29 Aug 2002 18:21:09 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Thu, 29 Aug 2002 18:15:36 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: Re: OLTC update - A problem! X-Mailing-List: archive/latest/1717 X-Loop: tesla@pupman.com Original poster: "davep by way of Terry Fritz " > It is really weird, I can take the secondary off and run the coil. The > energies are much the same, Measured? > but without a secondary, where in the world does the power go?! Into mag fields, floating thru the room. Some stray eddy current heating of nearby metallic objects. > I guess I should run the coil at full power to "find out", but I think the > answer would be "unpleasant" :-)) My guess is that the IGBTs will absorb > the power if nothing else does. I'd expect the phase of the current/power to be different. Speculation: Does this sort of test contribute anything to the 'efficiency' discussion? best dwp ...the net of a million lies... Vernor Vinge There are Many Web Sites which Say Many Things. -me Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Sun, 25 Aug 2002 12:29:03 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Sun, 25 Aug 2002 12:26:20 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: Re: OLTC update - Coupling figured out :-) X-Mailing-List: archive/latest/1514 X-Loop: tesla@pupman.com Original poster: "Terry Fritz" Hi Ken, I am using only about a 75 volt firing voltage right now (starting out real slow). But perhaps at these low levels the losses are higher and loosing power to the primary coil which just "looks" like very high coupling. From the scope trace at: http://hot-streamer.com/temp/OLTC08-24-01.gif The secondary losses are fine, but not sure about the primary. I will check into this. I may just have to keep cranking it up and the problem will go away ;-) YEP! Your right! I ran MicroSim with more realistic "low power" losses and got: http://hot-streamer.com/temp/OLTC08-25-01.gif That is indeed what I am seeing. The coupling is fine after all. There is NO problem. I just need to keep cranking the power up and the losses will reduce naturally. Thanks for the insight here!! It would have taken "me" a long time to figure this one out ;-)) I am surprised your coil has such a long ring up. Unless the coupling is very low, which a I doubt, Perhaps the square waves don't couple as well. Only the Fo sine component may be doing the coupling while the higher order harmonics of the square wave are either not coupling or "fighting" each other. An interesting and unknown problem, exciting a two coil system with square waves instead of sine waves... Maybe Paul's program could analyze such a case since the harmonics in the secondary may easily come into play in such a case. Simple MicroSim models may not see the true action there. I will try to run some models on this and see if I can figure anything out. BTW - I think I know of a very easy way to measure the primary current. Just a loop of wire under the primary (or near it) to a scope probe. The voltage on the loop should be proportional to the current (or maybe it needs a load resistor?). A simple and very useful instrument whose details will have to wait for another day... Cheers, Terry At 09:31 AM 8/25/2002 -0700, you wrote: >Terry (& all)- > >I've been following the OLTC saga off & on. But it's just occurred to me >that you may find yourself up against the situation I've found with my >s.s. coil: As you may recall, I apply a ~1200 V pp square-wave burst, of >up to ~6 ms duration, to a 3-turn (untuned) primary circuit for each >spark. With a 140 KHz secondary Fr and a 6" x 24" smooth (Landergren) >toroid, it takes ~30 cycles of constant (not exponentially declining!) >excitation to bring the toroid potential up to the spark break-out level. > >You are applying, I believe, ~680 x 2.8 = ~1900 V pp, initially, to a >3-turn primary circuit--incorporating much less resistance, admittedly, >than mine--but your excitation must (necessarily) exponentially-decline >quite rapidly. I'd think you might require more or less those 30 cycles >to pump up the voltage & I fear that the decline of your primary voltage >may preclude that. > >Were you able to do any simulations on that? > >Ken Herrick > >On Sat, 24 Aug 2002 23:02:13 -0600 "Tesla list" >writes: >> Original poster: "Terry Fritz" >> >> Hi All, >> >> Today I set up the coil for action: >> >> http://hot-streamer.com/temp/OLTC08-24-02.jpg >> >> I powered up the coil... > >[snipped] > > > Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Sun, 25 Aug 2002 13:41:03 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Sun, 25 Aug 2002 13:31:13 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: Re: OLTC update - Coupling figured out :-) X-Mailing-List: archive/latest/1515 X-Loop: tesla@pupman.com Original poster: "jimmy hynes by way of Terry Fritz " the reason kens coil has such a slow ring up is that the switches cant handle any more power. with most coils and the oltc that is not a problem, because it is actually less stress on the switch the faster the energy is transferred. in the oltc the turns are in parralell making it like less than one turn instead of 3 turns. if you use ten big igbts in a s.s coil it would be possible to get quick ring ups on even bigger coils. using a switch as a spark gap isnt as efficient as using it in a s.s. coil Tesla list wrote: > > Original poster: "Terry Fritz" > > Hi Ken, > > I am using only about a 75 volt firing voltage right now (starting out real > slow). But perhaps at these low levels the losses are higher and loosing > power to the primary coil which just "looks" like very high coupling. From > the scope trace at: > > http://hot-streamer.com/temp/OLTC08-24-01.gif > > The secondary losses are fine, but not sure about the primary. I will > check into this. I may just have to keep cranking it up and the problem > will go away ;-) > > YEP! Your right! I ran MicroSim with more realistic "low power" losses > and got: > > http://hot-streamer.com/temp/OLTC08-25-01.gif > > That is indeed what I am seeing. The coupling is fine after all. There is > NO problem. I just need to keep cranking the power up and the losses will > reduce naturally. > > Thanks for the insig! ht here!! It would have taken "me" a long time to > figure this one out ;-)) > > I am surprised your coil has such a long ring up. Unless the coupling is > very low, which a I doubt, Perhaps the square waves don't couple as well. > Only the Fo sine component may be doing the coupling while the higher order > harmonics of the square wave are either not coupling or "fighting" each > other. An interesting and unknown problem, exciting a two coil system with > square waves instead of sine waves... Maybe Paul's program could analyze > such a case since the harmonics in the secondary may easily come into play > in such a case. Simple MicroSim models may not see the true action there. > > I will try to run some models on this and see if I can figure anything out. > > BTW - I think I know of a very easy way to measure the primary current. > Just a loop of wire under the primary (or near it) to a scope probe. The > voltage on the loop should be proportional to the ! current (or maybe it > needs a load resistor?). A simple and v! ery useful instrument whose details > will have to wait for another day... > > Cheers, > > Terry > > > At 09:31 AM 8/25/2002 -0700, you wrote: > >Terry (& all)- > > > >I've been following the OLTC saga off & on. But it's just occurred to me > >that you may find yourself up against the situation I've found with my > >s.s. coil: As you may recall, I apply a ~1200 V pp square-wave burst, of > >up to ~6 ms duration, to a 3-turn (untuned) primary circuit for each > >spark. With a 140 KHz secondary Fr and a 6" x 24" smooth (Landergren) > >toroid, it takes ~30 cycles of constant (not exponentially declining!) > >excitation to bring the toroid potential up to the spark break-out level. > > > >You are applying, I believe, ~680 x 2.8 = ~1900 V pp, initially, to a > >3-turn primary circuit--incorporating much less resistance, admittedly, > >than mine--but your excitation must (necessarily) exponentially-decline > ! >quite rapidly. I'd think you might require more or less those 30 cycles > >to pump up the voltage & I fear that the decline of your primary voltage > >may preclude that. > > > >Were you able to do any simulations on that? > > > >Ken Herrick > > > >On Sat, 24 Aug 2002 23:02:13 -0600 "Tesla list" > >writes: > >> Original poster: "Terry Fritz" > >> > >> Hi All, > >> > >> Today I set up the coil for action: > >> > >> http://hot-streamer.com/temp/OLTC08-24-02.jpg > >> > >> I powered up the coil... > > > >[snipped] > > > > > > JImmy Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Sun, 25 Aug 2002 15:21:48 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Sun, 25 Aug 2002 15:18:25 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: Re: OLTC update - Coupling figured out :-) X-Mailing-List: archive/latest/1516 X-Loop: tesla@pupman.com Original poster: "K. C. Herrick by way of Terry Fritz " Terry (& all)- Figure -25 appears to show the secondary voltage reaching max. at the 2nd half-cycle and that is, indeed, extremely good. I should think you'd be able to see that directly on the scope by just laying your probe out as a little antenna, as I do. If my pet theory, as to voltage rate-of-rise vs. spark-progression time, is true, however, that high rate may not do you much good in increasing spark length, at just 30-odd KHz. Getting up there in 1 cycle at 140 KHz would be a different thing entirely. As to why my system takes its 30 cycles to ring up--don't know yet. My secondary sits directly on the primary, with spacing of perhaps 1" from the top of the primary bundle to the first secondary turn and having the same nominal 12" diameter. Certainly, if I could drive it with a sine wave with all else being equal, I suppose I would. But the MOSFETs have to turn on hard, of course. Also, it strikes me that the harmonic content of my voltage square wave will not elicit a lot of primary current because the impedance of the primary is a lot higher for those components. So...let it be square, as far as I can see. And as to harmonics "fighting" each other...say what? Does such a thing happen?? Not per anything I learned 50 years ago...but then one forgets, or never learned in the first place, a lot. I'd made a rough measurement many months ago that seemed to show that I got the best coupling to the secondary with a (larger diameter) primary located about 6" up (on a ~36" coil). Once I get my system up & running again (after the current irksome task of changing out 8 MOSFET-driver transistors for huskier ones), perhaps I'll make such a coil. And by the way, what is the mechanism that will cause your losses to decrease with increased input current? Ken On Sun, 25 Aug 2002 12:26:20 -0600 "Tesla list" writes: > Original poster: "Terry Fritz" > > Hi Ken, > > I am using only about a 75 volt firing voltage right now (starting > out real > slow). But perhaps at these low levels the losses are higher and > loosing > power to the primary coil which just "looks" like very high > coupling. From > the scope trace at: > > http://hot-streamer.com/temp/OLTC08-24-01.gif > > The secondary losses are fine, but not sure about the primary. I > will > check into this. I may just have to keep cranking it up and the > problem > will go away ;-) > > YEP! Your right! I ran MicroSim with more realistic "low power" > losses > and got: > > http://hot-streamer.com/temp/OLTC08-25-01.gif > > That is indeed what I am seeing. The coupling is fine after all. > There is > NO problem. I just need to keep cranking the power up and the > losses will > reduce naturally. > > Thanks for the insight here!! It would have taken "me" a long time > to > figure this one out ;-)) > > I am surprised your coil has such a long ring up. Unless the > coupling is > very low, which a I doubt, Perhaps the square waves don't couple as > well. > Only the Fo sine component may be doing the coupling while the > higher order > harmonics of the square wave are either not coupling or "fighting" > each > other. An interesting and unknown problem, exciting a two coil > system with > square waves instead of sine waves... Maybe Paul's program could > analyze > such a case since the harmonics in the secondary may easily come > into play > in such a case. Simple MicroSim models may not see the true action > there. > > I will try to run some models on this and see if I can figure > anything out. > > BTW - I think I know of a very easy way to measure the primary > current. > Just a loop of wire under the primary (or near it) to a scope probe. > The > voltage on the loop should be proportional to the current (or maybe > it > needs a load resistor?). A simple and very useful instrument whose > details > will have to wait for another day... > > Cheers, > > Terry > > > At 09:31 AM 8/25/2002 -0700, you wrote: > >Terry (& all)- > > > >I've been following the OLTC saga off & on. But it's just occurred > to me > >that you may find yourself up against the situation I've found with > my > >s.s. coil: As you may recall, I apply a ~1200 V pp square-wave > burst, of > >up to ~6 ms duration, to a 3-turn (untuned) primary circuit for > each > >spark. With a 140 KHz secondary Fr and a 6" x 24" smooth > (Landergren) > >toroid, it takes ~30 cycles of constant (not exponentially > declining!) > >excitation to bring the toroid potential up to the spark break-out > level. > > > >You are applying, I believe, ~680 x 2.8 = ~1900 V pp, initially, > to a > >3-turn primary circuit--incorporating much less resistance, > admittedly, > >than mine--but your excitation must (necessarily) > exponentially-decline > >quite rapidly. I'd think you might require more or less those 30 > cycles > >to pump up the voltage & I fear that the decline of your primary > voltage > >may preclude that. > > > >Were you able to do any simulations on that? > > > >Ken Herrick > > > >On Sat, 24 Aug 2002 23:02:13 -0600 "Tesla list" > >writes: > >> Original poster: "Terry Fritz" > >> > >> Hi All, > >> > >> Today I set up the coil for action: > >> > >> http://hot-streamer.com/temp/OLTC08-24-02.jpg > >> > >> I powered up the coil... > > > >[snipped] > > > > > > > > > > Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Sun, 25 Aug 2002 15:41:25 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Sun, 25 Aug 2002 15:39:55 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: Re: OLTC update - Coupling figured out :-) X-Mailing-List: archive/latest/1517 X-Loop: tesla@pupman.com Original poster: "Terry Fritz" Hi Ken, At 02:13 PM 8/25/2002 -0700, you wrote: >Terry (& all)- > >Figure -25 appears to show the secondary voltage reaching max. at the 2nd >half-cycle and that is, indeed, extremely good. I should think you'd be >able to see that directly on the scope by just laying your probe out as a >little antenna, as I do. I can see it in my plane wave antenna which is just the same thing as a wire antenna but with a flat frequency response. That is how I first noticed this. what we see is the normal ringup of the secondary but it runs out of gas suddenly. It "was" going to ring up much further and longer but it suddenly had no more power. > >If my pet theory, as to voltage rate-of-rise vs. spark-progression time, >is true, however, that high rate may not do you much good in increasing >spark length, at just 30-odd KHz. Getting up there in 1 cycle at 140 KHz >would be a different thing entirely. The fast ringup thing just shows there is not enough primary power or too much loss. The actual energy transfer time is sort and not very efficient. > >As to why my system takes its 30 cycles to ring up--don't know yet. My >secondary sits directly on the primary, with spacing of perhaps 1" from >the top of the primary bundle to the first secondary turn and having the >same nominal 12" diameter. Certainly, if I could drive it with a sine >wave with all else being equal, I suppose I would. But the MOSFETs have >to turn on hard, of course. Also, it strikes me that the harmonic >content of my voltage square wave will not elicit a lot of primary >current because the impedance of the primary is a lot higher for those >components. So...let it be square, as far as I can see. It may be just fine. I was just reminded of the wild voltage transients Paul's programs predict in some situations. A square wave case would be interesting to check. > >And as to harmonics "fighting" each other...say what? Does such a thing >happen?? Not per anything I learned 50 years ago...but then one forgets, >or never learned in the first place, a lot. I don't know if that could happen or not. Be interesting to study it. > >I'd made a rough measurement many months ago that seemed to show that I >got the best coupling to the secondary with a (larger diameter) primary >located about 6" up (on a ~36" coil). Once I get my system up & running >again (after the current irksome task of changing out 8 MOSFET-driver >transistors for huskier ones), perhaps I'll make such a coil. > >And by the way, what is the mechanism that will cause your losses to >decrease with increased input current? The IGBTs tend to have linear losses (unlike FETs that have I^2 loss) with increased drive current while the coil's power goes up as a square function of current. So ten times the input voltage gives ten times the loss but 100 times the power. It appears that the coil becomes more efficient overall with the more power it has available. Much more to study in all this ;-)) Cheers, Terry > >Ken > >On Sun, 25 Aug 2002 12:26:20 -0600 "Tesla list" >writes: >> Original poster: "Terry Fritz" >> >> Hi Ken, >> >> I am using only about a 75 volt firing voltage right now (starting >> out real >> slow). But perhaps at these low levels the losses are higher and >> loosing >> power to the primary coil which just "looks" like very high >> coupling. From >> the scope trace at: >> >> http://hot-streamer.com/temp/OLTC08-24-01.gif >> >> The secondary losses are fine, but not sure about the primary. I >> will >> check into this. I may just have to keep cranking it up and the >> problem >> will go away ;-) >> >> YEP! Your right! I ran MicroSim with more realistic "low power" >> losses >> and got: >> >> http://hot-streamer.com/temp/OLTC08-25-01.gif >> >> That is indeed what I am seeing. The coupling is fine after all. >> There is >> NO problem. I just need to keep cranking the power up and the >> losses will >> reduce naturally. >> >> Thanks for the insight here!! It would have taken "me" a long time >> to >> figure this one out ;-)) >> >> I am surprised your coil has such a long ring up. Unless the >> coupling is >> very low, which a I doubt, Perhaps the square waves don't couple as >> well. >> Only the Fo sine component may be doing the coupling while the >> higher order >> harmonics of the square wave are either not coupling or "fighting" >> each >> other. An interesting and unknown problem, exciting a two coil >> system with >> square waves instead of sine waves... Maybe Paul's program could >> analyze >> such a case since the harmonics in the secondary may easily come >> into play >> in such a case. Simple MicroSim models may not see the true action >> there. >> >> I will try to run some models on this and see if I can figure >> anything out. >> >> BTW - I think I know of a very easy way to measure the primary >> current. >> Just a loop of wire under the primary (or near it) to a scope probe. >> The >> voltage on the loop should be proportional to the current (or maybe >> it >> needs a load resistor?). A simple and very useful instrument whose >> details >> will have to wait for another day... >> >> Cheers, >> >> Terry >> >> >> At 09:31 AM 8/25/2002 -0700, you wrote: >> >Terry (& all)- >> > >> >I've been following the OLTC saga off & on. But it's just occurred >> to me >> >that you may find yourself up against the situation I've found with >> my >> >s.s. coil: As you may recall, I apply a ~1200 V pp square-wave >> burst, of >> >up to ~6 ms duration, to a 3-turn (untuned) primary circuit for >> each >> >spark. With a 140 KHz secondary Fr and a 6" x 24" smooth >> (Landergren) >> >toroid, it takes ~30 cycles of constant (not exponentially >> declining!) >> >excitation to bring the toroid potential up to the spark break-out >> level. >> > >> >You are applying, I believe, ~680 x 2.8 = ~1900 V pp, initially, >> to a >> >3-turn primary circuit--incorporating much less resistance, >> admittedly, >> >than mine--but your excitation must (necessarily) >> exponentially-decline >> >quite rapidly. I'd think you might require more or less those 30 >> cycles >> >to pump up the voltage & I fear that the decline of your primary >> voltage >> >may preclude that. >> > >> >Were you able to do any simulations on that? >> > >> >Ken Herrick >> > >> >On Sat, 24 Aug 2002 23:02:13 -0600 "Tesla list" >> >writes: >> >> Original poster: "Terry Fritz" >> >> >> >> Hi All, >> >> >> >> Today I set up the coil for action: >> >> >> >> http://hot-streamer.com/temp/OLTC08-24-02.jpg >> >> >> >> I powered up the coil... >> > >> >[snipped] >> > >> > >> > >> >> >> >> > Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Sun, 25 Aug 2002 15:46:03 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Sun, 25 Aug 2002 15:40:34 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: Re: OLTC update - Coupling figured out :-) X-Mailing-List: archive/latest/1518 X-Loop: tesla@pupman.com Original poster: "by way of Terry Fritz " In a message dated 8/25/02 5:20:36 PM Eastern Daylight Time, tesla@pupman.com writes: > > As to why my system takes its 30 cycles to ring up--don't know yet. Ken, I thought your coil took 30 cycles to ring up because this is the resonator fill-time. It was my understanding that a CW system took about 30 cyles to ring up if the effective Q of the system was about 30. You're pumping up the voltage over successive cycles by virtue of the steady application of energy to the system, which can go no higher when the input energy vs. losses is balanced. This is much different than a damped wave situation, where ring-up time is based mostly on the coupling for a given frequency. Perhaps the coupling aspect applies somewhat in your CW situation but is hidden by the CW effects. I'm not an expert in this area, but I think the general idea is correct. John Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Sun, 25 Aug 2002 15:46:47 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Sun, 25 Aug 2002 15:44:33 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: Re: OLTC update - Coupling figured out :-) X-Mailing-List: archive/latest/1519 X-Loop: tesla@pupman.com Original poster: "K. C. Herrick by way of Terry Fritz " Jimmy (& all)- Yes, you remind me that Terry's turns are in parallel whereas mine are in series, and that does give him a whole lot less resistance. But I think that yields him exactly 1 turn, and not less than 1: you can't get from here back to here in less than 1 turn. I believe I could approach that if I used IGBTs instead of MOSFETs, and 1 (equivalent) turn instead of 3. But I don't think IGBTs are going to switch satisfactorily at 140 KHz--unless they've been improved a lot since I last looked. As to the efficiency of a s.s. switch in one configuration vs. the other, I'd think it wouldn't matter much. Not so? Ken Herrick On Sun, 25 Aug 2002 13:31:13 -0600 "Tesla list" writes: > Original poster: "jimmy hynes by way of Terry Fritz > " > > > the reason kens coil has such a slow ring up is that the switches > cant handle > any more power. with most coils and the oltc that is not a problem, > because it > is actually less stress on the switch the faster the energy is > transferred. in > the oltc the turns are in parralell making it like less than one > turn instead > of 3 turns. if you use ten big igbts in a s.s coil it would be > possible to get > quick ring ups on even bigger coils. using a switch as a spark gap > isnt as > efficient as using it in a s.s. coil [snipped] Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Mon, 26 Aug 2002 00:24:20 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Mon, 26 Aug 2002 00:07:58 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: Re: OLTC update - Coupling figured out :-) X-Mailing-List: archive/latest/1522 X-Loop: tesla@pupman.com Original poster: "Malcolm Watts by way of Terry Fritz " Hi Terry, Ken et all, I've been following the OLTC development with much interest. On 25 Aug 2002, at 12:26, Tesla list wrote: > Original poster: "Terry Fritz" > > Hi Ken, > > I am using only about a 75 volt firing voltage right now (starting out real > slow). But perhaps at these low levels the losses are higher and loosing > power to the primary coil which just "looks" like very high coupling. From > the scope trace at: > > http://hot-streamer.com/temp/OLTC08-24-01.gif That is very probable. k after all is a geometry thing. Have you yet calculated your primary Q from its ringing down alone? I expect that will fill a big gap in the story. If it only rings for a few cycles, you know the losses are big. I agree that the proportional losses will be higher at low primary voltages. Your situation is totally different from a CW-driven coil. The cap rings down to empty whereas the CW coil feeds in a constant amount of energy per cycle as long as the primary is ringing (at constant amplitude). > The secondary losses are fine, but not sure about the primary. I will > check into this. I may just have to keep cranking it up and the problem > will go away ;-) What is you unloaded secondary Q? > YEP! Your right! I ran MicroSim with more realistic "low power" losses > and got: > > http://hot-streamer.com/temp/OLTC08-25-01.gif > > That is indeed what I am seeing. The coupling is fine after all. There is > NO problem. I just need to keep cranking the power up and the losses will > reduce naturally. > > Thanks for the insight here!! It would have taken "me" a long time to > figure this one out ;-)) > > I am surprised your coil has such a long ring up. That is to be expected since the primary doesn't decrement. No surprise there. The coils are running under different conditions. Regards, malcolm Unless the coupling is > very low, which a I doubt, Perhaps the square waves don't couple as well. > Only the Fo sine component may be doing the coupling while the higher order > harmonics of the square wave are either not coupling or "fighting" each > other. An interesting and unknown problem, exciting a two coil system with > square waves instead of sine waves... Maybe Paul's program could analyze > such a case since the harmonics in the secondary may easily come into play > in such a case. Simple MicroSim models may not see the true action there. > > I will try to run some models on this and see if I can figure anything out. > > BTW - I think I know of a very easy way to measure the primary current. > Just a loop of wire under the primary (or near it) to a scope probe. The > voltage on the loop should be proportional to the current (or maybe it > needs a load resistor?). A simple and very useful instrument whose details > will have to wait for another day... > > Cheers, > > Terry > > > At 09:31 AM 8/25/2002 -0700, you wrote: > >Terry (& all)- > > > >I've been following the OLTC saga off & on. But it's just occurred to me > >that you may find yourself up against the situation I've found with my > >s.s. coil: As you may recall, I apply a ~1200 V pp square-wave burst, of > >up to ~6 ms duration, to a 3-turn (untuned) primary circuit for each > >spark. With a 140 KHz secondary Fr and a 6" x 24" smooth (Landergren) > >toroid, it takes ~30 cycles of constant (not exponentially declining!) > >excitation to bring the toroid potential up to the spark break-out level. > > > >You are applying, I believe, ~680 x 2.8 = ~1900 V pp, initially, to a > >3-turn primary circuit--incorporating much less resistance, admittedly, > >than mine--but your excitation must (necessarily) exponentially-decline > >quite rapidly. I'd think you might require more or less those 30 cycles > >to pump up the voltage & I fear that the decline of your primary voltage > >may preclude that. > > > >Were you able to do any simulations on that? > > > >Ken Herrick > > > >On Sat, 24 Aug 2002 23:02:13 -0600 "Tesla list" > >writes: > >> Original poster: "Terry Fritz" > >> > >> Hi All, > >> > >> Today I set up the coil for action: > >> > >> http://hot-streamer.com/temp/OLTC08-24-02.jpg > >> > >> I powered up the coil... > > > >[snipped] > > > > > > > > > Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Mon, 26 Aug 2002 00:24:07 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Mon, 26 Aug 2002 00:10:40 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: Re: OLTC update - Coupling figured out :-) X-Mailing-List: archive/latest/1527 X-Loop: tesla@pupman.com Original poster: "jimmy hynes by way of Terry Fritz " terry's three turns in parralell would act like 1 turn if they were perfectly coupled, however because the coupling isnt perfect the inductance goes down a little. i was thinking about making a sstc with igbts and a quick rise time. i found some igbts that could be used in hard switching applications up to 150khz. another one said 40khz in hard switching and >200 khz in resonant switching. i intuitively guessed that ss spark gaps would be less efficien than sstcs. i checked that by making pspice models of both, it looked like (at k=.15) i could get the same rise time with about 1/5 the average current as in a spark gap design. with high coupling i guess ss spark gaps could do as good. wouldn't higher k be attainable because of the electronic quenching? i know you would still have to worry about the insulation, but it seems like you could find a good way to fix that. Tesla list > > wrote: > Original poster: "K. C. Herrick by way of Terry Fritz " > > Jimmy (& all)- > > Yes, you remind me that Terry's turns are in parallel whereas mine are in > series, and that does give him a whole lot less resistance. But I think > that yields him exactly 1 turn, and not less than 1: you can't get from > here back to here in less than 1 turn. I believe I could approach that > if I used IGBTs instead of MOSFETs, and 1 (equivalent) turn instead of 3. > But I don't think IGBTs are going to switch satisfactorily at 140 > KHz--unless they've been improved a lot since I last looked. > > As to the efficiency of a s.s. switch in one configuration vs. the other, > I'd think it wouldn't matter much. Not so? > > Ken Herrick > > On Sun, 25 Aug 2002 13:31:13 -0600 "Tesla list" > writes: > > Original poster: "jimmy hyn! es by way of Terry Fritz > > " > > > > > > the reason kens coil has such a slow ring up is that the switches > > cant handle > > any more power. with most coils and the oltc that is not a problem, > > because it > > is actually less stress on the switch the faster the energy is > > transferred. in > > the oltc the turns are in parralell making it like less than one > > turn instead > > of 3 turns. if you use ten big igbts in a s.s coil it would be > > possible to get > > quick ring ups on even bigger coils. using a switch as a spark gap > > isnt as > > efficient as using it in a s.s. coil > > [snipped] > > > > > > > > JImmy > Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Mon, 7 Oct 2002 22:01:38 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Mon, 07 Oct 2002 21:57:09 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: OLTC update - Curiouser and curiouser! X-Mailing-List: archive/latest/3916 X-Loop: tesla@pupman.com Original poster: "Terry Fritz" Hi All, I was running numbers and models today when I noticed that this picture of base current (blue) sure has a long ringdown time (like 2mS!!!):O http://hot-streamer.com/temp/OLTC10-05-03.gif There was no breakout in these low power tests but a 2mS ring down time was easy to see as "odd" compared to the models! So I fiddled around and finally took the following data: Pinger PK FREQ kHz (Error +/-) Q FACTOR (Error +/-) LEVEL 1 37.229 (0.01%,3Hz) 84.19 (0.09%, 0.1) -0.4dB 2 113.864 (0.01%,8Hz) 46.26 (0.70%, 0.3) -12.3dB 3 172.448 (0.01%,12Hz) 34.37 (2.79%, 1.0) -17.0dB 4 223.862 (0.01%,16Hz) 29.69 (11.17%, 3.3) -20.3dB 5 273.388 (0.01%,19Hz) 25.94 (18.78%, 4.9) -24.1dB 6 273.391 (0.01%,19Hz) 26.01 (18.78%, 4.9) -24.0dB Running Coil PK FREQ kHz (Error +/-) Q FACTOR (Error +/-) LEVEL 1 37.148 (0.01%,2Hz) 83.73 (0.49%, 0.4) 0.0dB 2 114.014 (0.01%,7Hz) 33.80 (22.33%, 7.5) -26.5dB 3 172.208 (0.01%,11Hz) 35.87 (7.90%, 2.8) -28.1dB 4 226.978 (0.01%,15Hz) 37.49 (18.78%, 7.0) -29.4dB 5 120.239 (0.01%,8Hz) 5.20 (100.00%, 5.2) -21.3dB 6 119.635 (0.01%,8Hz) 7.28 (18.78%, 1.4) -23.3dB The Q seems to have almost exactly doubled to 84 now!! Of course, I am not complaining ;-)) but I am thinking the SonoTube picked up humidity originally and it is slowly drying out over time. The Q of SonoTube is wildly affected by humidity. I really can't recommend it for TC use anymore even if it is fast and cheap. TCMA did not find PK5 in the normal running coil test above and PK2 was odd. I think that may be due to the gap still conducting in one direction with the IGBTS? That should affect the harmonics. My models are very accurate these days: http://hot-streamer.com/temp/OLTC10-07-01.gif I can now completely model the 240BPS case and actually understand the "why" behind it all. Having the IGBTs conduct during the negative swing does allow for odd sweet spots in coupling and timing. I need to play with that more. Also the models predict some noise spikes that are not really there. The new P5202 probe is helping a lot finding the "real" waveforms ;-) I have to tune the models there, Probably stray capacitance somewhere is eating those spikes that the "theoretical" case is missing. Last night I switched to new transorbs (two 650 volt strings) in preparation for 240VAC operation. Voltage spikes are not a problem if it is tuned right but if something goes wrong or I am playing with the knobs, they protect the IGBTs. I also put in 7 amps fuses but that was not rocket science ;-) I think I am going to have to make a new IGBT driver for 27 volt drive. My present box just is not right. I will also add a third (maybe forth) stage for 15 IGBTs in the new design. I may try my present one first to see if maybe going to 20 IGBTs would be a good thing. Since IGBT destruction is not a problem, I can go for the full setup there and lower the astronomical currents they see now. I may also go to two small 12 Volt gel cells for drive. 9v batteries tend to drain vary fast. I have a nice dual charger from my robot stuff that could easily charge them so it would not be a big deal to do that way. I am probably hitting the gate at 360BPS right now and it seems to be too much power for the little 9 volt batteries to take for long. If they discharge, they could cause low gate drive which is "bad"... 240VAC may need lower coupling since primary to secondary arcing is right on edge now at 120VAC. That would change timing and all a bit. Hard to say there... I think more IGBTs would really help primary Q and I am getting very convinced a plastic secondary would really help secondary Q (although, at 600 ohms, is "good enough" now). If I can successfully get it to 240VAC, that is 4X the power ;-)) I certainly don't see any reason why it can't do that other than it is "getting close" on primary current for the present system and primary to secondary arcing is a problem. I still don't know about gate drive resistance. Lower resistance would help some things but it would also increase transients as switching speed increases. Need more thought there. Cheers, Terry Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Fri, 30 Aug 2002 23:53:57 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Fri, 30 Aug 2002 23:50:20 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: OLTC update - good news :-)) X-Mailing-List: archive/latest/1773 X-Loop: tesla@pupman.com Original poster: "Terry Fritz" Hi All, Some good news. I got some spare IGBTs from DigiKey and tested them at high current using this fast setup that is sort of close to the real OLTC application: http://hot-streamer.com/temp/OLTC08-30-01.jpg I managed to run one at over 700 amps!!! http://hot-streamer.com/temp/OLTC08-30-02.gif What is cool is that I seem to have gone higher if I had more gate voltage. Everything was rock stable and you could easily see the current limit as the IGBT starved for gate drive for more even more current. It just mildly started to dissipate more heat and all as it lost full conduction. But it still didn't explode or anything (just a 'tiny' heat sink on it). So they 'can' be run well over their rating (204 amps) and survive. This means I should be able to easily run my coil of 240 VAC with the ten IGBTs I have without having to add more or making major changes :-))) BTW - Very interesting post from Greg Leyh tonight!!! I will need to modify things a little bit: 1. I should change the gate drive resistors to 10 ohms instead of 100. These IGBTs don't seem to have any problem with low gate drive resistance even at very high currents. The transorbs can take care of the shoot through effects, if any. 2. I will see if I can go to 27 volt gate drive instead of 18 volts (3 batteries instead of 2). I am a bit worried as the 9 volt batteries wear down that they may go too low in voltage which would be "bad". With three batteries and 30V transorbs, I would have plenty of margin. 27V is well over the gate "spec" voltage but that does not worry me at all (me and Marco will have to talk on that ;-)) 3. I have to remember to change the gate transorbes to 30 volts and the rail ones to 600 volts... Watch me forget that one :o)) BTW - Marco wanted to see the gate voltages: http://hot-streamer.com/temp/OLTC08-30-03.gif It's the red line. I hate these differential measurements especially with cheap 100:1 voltage probes like I used here. But there it is... The scope picture at: http://hot-streamer.com/temp/OLTC08-30-02.gif Is really very interesting. You can see where the IGBT turned off just after the forth top hump. The reverse diode conducted what was left of the negative side current. Then, the waveform stopped like a rock. An amazing feat considering the current and the one poor little device that was doing it ;-)) I imagine the transorbes across the "coil" were seeing some spikes but they seemed to handle it just fine. Jimmy's post and Paul's secondary virtual data base seem to suggest that my secondary Q should be more like 200 rather than only 36. So I probably screwed something up there. I bet it was the SonoTube. I was in a hurry and just picked that up instead of a nice PVC tube... Oh oh!!!........... Paul just wrote me back with a tcma Q of 45 :-P So,.... It may get messy... Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Sat, 31 Aug 2002 12:19:42 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Sat, 31 Aug 2002 11:58:42 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: Re: OLTC update - good news :-)) X-Mailing-List: archive/latest/1785 X-Loop: tesla@pupman.com Original poster: "by way of Terry Fritz " In a message dated 8/31/02 1:53:01 AM Eastern Daylight Time, tesla@pupman.com writes: << 2. I will see if I can go to 27 volt gate drive instead of 18 volts (3 batteries instead of 2). I am a bit worried as the 9 volt batteries wear down that they may go too low in voltage which would be "bad". With three batteries and 30V transorbs, I would have plenty of margin. 27V is well over the gate "spec" voltage but that does not worry me at all (me and Marco will have to talk on that ;-)) >> Why not just use a seperate PSU for this?Transformer and brige with filter or regulator. Matt Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Wed, 4 Sep 2002 22:32:43 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Wed, 04 Sep 2002 22:30:08 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: OLTC Update - OLTC-2 X-Mailing-List: archive/latest/2072 X-Loop: tesla@pupman.com Original poster: "Terry Fritz" Hi All, Today I have pondered many things... The present OLTC works wildly well considering what a total disaster it could have been :-)) There were only two issues that turned out as serious problems. 1. Primary losses are higher than expected. The primary loss should have been 500uOhms instead of 3mOhms. Miscalculations on my part and higher Vce that expected in the IGBTs... Probably be hard to get a primary Q of over 40 in an OLTC (normal TC is about Q=50). However, the very high coupling and perfect quenching of the OLTC can easily make up for this. 2. Secondary losses... While not a big issue with conventional coil (or, maybe it is??), it certainly made it's presence known here! Never expected this one ;-)) Not a basic OLTC problem but a general Tesla coiling issue that was amplified in this case. Redesign can fix this... Comparing The OLTC to a conventional TC of the same primary energy with a model: http://hot-streamer.com/temp/OLTC09-04-01.gif We see the initial trapped secondary voltage is about the same: http://hot-streamer.com/temp/OLTC09-04-03.gif But the high loss of the secondary eats a lot of power: http://hot-streamer.com/temp/OLTC09-04-02.gif We need a much better secondary... Things that worked! 1. Parallel IGBTs with anti-parallel diodes are a big winner! They are very stable and can takes LOTs of current. Very good quenching and control. 2. Having a primary cap per IGBT to control current sharing is also a major advantage! 3. Although it messes up our pretty computer models. Multiple primary loops in parallel to reduce primary inductance works very well. It may also be the key that allows much higher primary to secondary coupling. 4. Resonant charging works very well. It adds a sort of heavy iron core inductor to the system but it is totally reliable and well behaved. 5. The IGBT firing and control system work perfectly. I just built it and it worked right off. and gives zero problems. 6. High coupling. This was an unexpected big bonus! I never thought I could run with 0.25 coupling. Need to take total advantage of this now. Never thought a one turn primary could do that! ;-)) 7. All the theory and modeling proved to work just fine. I didn't know some of the "right" numbers but there was no great oversights or boo boos. It all worked just as it should. 8. It didn't blow up! It never broke. The thing is rock solid and reliable. So before, it was all new and in the dark, but now it is very well known (probably better understood than any conventional TC!) So we know it all now ;-)) The present coil can't be modified to improve it much. The secondary losses require a pretty radical physical change. Best just to leave it as is. There is not much to it so Making a whole new coil is not a big deal. So it's time for a new coil. The changes that need to be made are: 1. Go to a very large diameter secondary. Maybe like 18 inches! This allows much higher Q using less and larger diameter wire. 2. Possibly go to a larger toroid. But realizing that the voltage ratio (Lsec/Lpri) needs to be maintained. 3. Possibly go to 15 IGBTs. That helps the losses and does not stress them with so much with super high current. Probably worth the added cost. 4. Put the primary inside the secondary. If the secondary is larger, all the electronics can go inside the primary with the secondary on the outside. 6. Don't use SonoTube. It is known for low Q. That is critical here. 7. Better balancing of everything for power transfer to the streamers. 8. Perhaps go to lower power but higher frequency with less primary capacitance. So I am think about the next coil to solve the Q problem. Cheers, Terry Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Thu, 5 Sep 2002 07:25:28 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Thu, 05 Sep 2002 07:14:06 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: Re: OLTC Update - OLTC-2 X-Mailing-List: archive/latest/2081 X-Loop: tesla@pupman.com Original poster: "tesla by way of Terry Fritz " Hi Terry tnx for the summary. Really amazing that the major performance issue really turned out to be the secondary. The whole story of the OLTC has taught many of us a lot. Did you ever consider whether a primary based on a cylindrical sheet instead of 3 tubes would be an advantage. Who knows maybe the IGBTs would mount on it too. Presumably it would allow very low L in a reasonably large diameter and may permit the primary to be kept outside the secondary where it can be got at easier. Rgds Ted L in NZ Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Thu, 5 Sep 2002 12:41:05 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Thu, 05 Sep 2002 12:34:59 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: RE: OLTC Update - OLTC-2 X-Mailing-List: archive/latest/2095 X-Loop: tesla@pupman.com Original poster: "Terry Fritz" Hi All, I ran a bunch of numbers today on the redesign. As it turns out, I apparently do not need more top capacitance but rather more inductance for higher Q and better streamer power transfer. http://hot-streamer.com/temp/OLTC09-05-01.gif This agrees with the equation: Q = 2 x pi x F x L / R Of course, as we add L we also ad R so we need to be careful. An 18 inch secondary about 36 inches long with a reasonable top load is going to have a secondary capacitance of about 40pF. Thus the secondary inductance will have to be about 400mH. Pretty close to what I have now. But if I can decrease the Rsec by 1/2, then the output power will equal that of a typical coil given the input power. http://hot-streamer.com/temp/OLTC09-05-03.gif http://hot-streamer.com/temp/OLTC09-05-04.gif Using my excel sheet I find that a reasonable coil could be about 1400 turns of #24: http://hot-streamer.com/temp/OLTC09-05-05.gif That gives 1/2 the number of turns and 63% of the DC resistance. Of course, I would also get rid of the high-loss SonoTube! I really don't know the true secondary frequency yet (other than it should be as high as possible (even lower Lpri!)) but these numbers show I really can get some serious power to the streamers taking care to consider the Q problems of before. Not to hard really once you see what's going on. I really need to see if I can get the frequency higher! Even if I have to lower the primary capacitance, I may gain power by reducing the secondary size and it's losses. So I'll begin work on the new coil and work on getting the original one up to 240VAC in the mean time. Cheers, Terry Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Thu, 5 Sep 2002 12:41:05 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Thu, 05 Sep 2002 12:36:49 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: Re: OLTC Update - OLTC-2 X-Mailing-List: archive/latest/2096 X-Loop: tesla@pupman.com Original poster: "by way of Terry Fritz " In a message dated 9/4/02 9:31:32 PM Pacific Daylight Time, tesla@pupman.com writes: - snip - > > So it's time for a new coil. The changes that need to be made are: > > 1. Go to a very large diameter secondary. Maybe like 18 inches! This > allows much higher Q using less and larger diameter wire. > > 2. Possibly go to a larger toroid. But realizing that the voltage ratio > (Lsec/Lpri) needs to be maintained. > > 3. Possibly go to 15 IGBTs. That helps the losses and does not stress them > with so much with super high current. Probably worth the added cost. > > 4. Put the primary inside the secondary. If the secondary is larger, all > the electronics can go inside the primary with the secondary on the outside. > > 6. Don't use SonoTube. It is known for low Q. That is critical here. > > 7. Better balancing of everything for power transfer to the streamers. > > 8. Perhaps go to lower power but higher frequency with less primary > capacitance. > > > So I am think about the next coil to solve the Q problem. > > Cheers, > > Terry Terry, Sounds good - but, when are you going to run this existing coil up to full power??? Ed Sonderman Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Thu, 5 Sep 2002 12:44:54 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Thu, 05 Sep 2002 12:42:00 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: Re: OLTC Update - OLTC-2 X-Mailing-List: archive/latest/2099 X-Loop: tesla@pupman.com Original poster: "Terry Fritz" >At 02:07 PM 9/5/2002 -0400, you wrote: > > >Terry, > >Sounds good - but, when are you going to run this existing coil up to full >power??? > >Ed Sonderman > Hi Ed, I will take some time to do some testing for Paul and fiddle with a few things and then we'll go to full power. Plenty of time while waiting for the parts for the new one to arrive ;-)) I had better do all this before since the secondary my get pretty warm right now!! Nice to get all the work done incase it fries... Cheers, Terry Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Fri, 30 Aug 2002 15:31:17 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Fri, 30 Aug 2002 15:21:09 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: OLTC update - Poor seconadry Q X-Mailing-List: archive/latest/1737 X-Loop: tesla@pupman.com Original poster: "Terry Fritz" Hi All, I have adjusted my coil as best I can but the output still seems "weak". I think I now know why. My secondary Q is only 36. That works out to a secondary AC resistance of about 3300 ohms!! R = 2 x pi x F x L / Q Paul - The pinger file is here if your are interested. http://hot-streamer.com/temp/OLTCsec.CSV The waveform is at: http://hot-streamer.com/temp/OLTC08-30-01.gif Just to give an idea of how bad this is... I am pumping and quenching 317 watts into the secondary system. 53 watts is going to streamers and a stunning 264 watts is going into heating up the secondary!!! So 83 percent of the power is "lost" :-(( Some notes are at: http://hot-streamer.com/temp/OLTCnotes.txt The entries at the last tell of the Q=36 case. So... I don't know if it is the SonoTube, surroundings, proximity effects, plastic wrap coating... Have to test some things... A small chance it could be the anti-parallel diodes... Of course, this is not a problem with the basic OLTC technology, that works great!, but rather an age old problem of making secondaries without really low Q... Of course, ideas on how I can fix this are more than welcome :-)) The specs of the secondary system are: L = 480mH Wire gauge = #28 Turns = 2760 Winding length = 41 inches Diameter = 10.75 inches Q = 36.0 :-p Fo = 38.2kHz Csec = 35pF Torroid 24" diameter x 6.5" cord Center or toroid 3.5 inches above last secondary turn. Cheers, Terry Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Fri, 30 Aug 2002 20:56:29 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Fri, 30 Aug 2002 20:54:03 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: Re: OLTC update - Poor seconadry Q X-Mailing-List: archive/latest/1764 X-Loop: tesla@pupman.com Original poster: "jimmy hynes by way of Terry Fritz " how do you know the q is so bad? did you measure it or calculate it? can you feel the secondary heating? also weak compared to other 300 watt coils you have made or seen or are you comparing it to johns formula for input power and park length? the formula might not be accurate at low powers, i doubt he looked at alot of 300 watt coils when making the formula. my calculations said the q should be around 200. i used the javatc to get a guess at the resistance. i dont trust my calculations too much because i didnt find the equations. i derived the equation myself, and i make alot of mistakes. Tesla list wrote: > > Original poster: "Terry Fritz" > > Hi All, > > I have adjusted my coil as best I can but the output still seems "weak". I > think I now know why. My secondary Q is only 36. That works out to a > secondary AC resistance of about 3300 ohms!! R = 2 x pi x F x L / Q > > Paul - The pinger file is here if your are interested. > > http://hot-streamer.com/temp/OLTCsec.CSV > > The waveform is at: > > http://hot-streamer.com/temp/OLTC08-30-01.gif > > Just to give an idea of how bad this is... I am pumping and quenching 317 > watts into the secondary system. 53 watts is going to streamers and a > stunning 264 watts is going into heating up the secondary!!! > > So 83 percent of the power is "lost" :-(( > > Some notes are at: > > http://hot-streamer.com/temp/OLTCnotes.txt > > The entries at the last tell of the Q=36 case. > > So... I don't k! now if it is the SonoTube, surroundings, proximity effects, > plastic wrap coating... Have to test some things... A small chance it > could be the anti-parallel diodes... > > Of course, this is not a problem with the basic OLTC technology, that works > great!, but rather an age old problem of making secondaries without really > low Q... > > Of course, ideas on how I can fix this are more than welcome :-)) > > The specs of the secondary system are: > > L = 480mH > Wire gauge = #28 > Turns = 2760 > Winding length = 41 inches > Diameter = 10.75 inches > Q = 36.0 :-p > Fo = 38.2kHz > Csec = 35pF > > Torroid 24" diameter x 6.5" cord > Center or toroid 3.5 inches above last secondary turn. > > Cheers, > > Terry > > JImmy Do You Yahoo!? Yahoo! Finance - Get real-time stock quotes Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Fri, 30 Aug 2002 22:04:46 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Fri, 30 Aug 2002 21:59:20 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: Re: OLTC update - Poor seconadry Q X-Mailing-List: archive/latest/1769 X-Loop: tesla@pupman.com Original poster: "Barton B. Anderson by way of Terry Fritz " Terry, Tesla list wrote: > Original poster: "Terry Fritz" > > So... I don't know if it is the SonoTube, surroundings, proximity effects, > plastic wrap coating... Have to test some things... A small chance it > could be the anti-parallel diodes... I think none of the above, but rather the secondary itself. I would bet the Q of the secondary by itself is pretty low. > Of course, ideas on how I can fix this are more than welcome :-)) Rewind a secondary with less turns and larger wire. Fres will tripple (not sure how tied into 0.47uF you are with the IGBT current). Of course, with all the work you put into this project already, I hope it's something else. BTW, if you were to model the secondary in JavaTC (since it was mentioned in another post), here are the input parameters for your coil: Sec Diam = 10.75 Sec Length = 41 Bare Wire Diam = 0.0126 Insulation = 0.001 Spacing = 0.000255 Toroid Major = 24 Toroid Minor = 6.5 Sphere Diam = 0 Top Load Reduction = 36.3 Here are some of the main outputs JavaTC identifies: DC Resistance = 507.53 ohms Inductance = 480.13 mH Self Fres = 52.4 kHz Skin depth = 0.014 inch Loaded Fres = 38.21 kHz Total Capacitance = 36.14pF Take care, Bart http://www.classictesla.com/java/javatc.html or http://www.classictesla.com/java/javatc92.html The bottom link is beta version 9.2 Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Sat, 31 Aug 2002 12:11:37 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Sat, 31 Aug 2002 11:54:40 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: Re: OLTC update - Poor seconadry Q X-Mailing-List: archive/latest/1783 X-Loop: tesla@pupman.com Original poster: "Bert Hickman by way of Terry Fritz " Hi Terry, I'd bet if you remove the secondary from the primary and re-measure it you'll see a Q more like 200. The primary "gap" is conducting on alternate half cycles, sapping energy from your secondary and lowering the effective Q. Best regards, -- Bert -- -- Bert Hickman Stoneridge Engineering "Electromagically" (TM) Shrunken Coins! http://www.teslamania.com Tesla list wrote: > > Original poster: "Terry Fritz" > > Hi All, > > I have adjusted my coil as best I can but the output still seems "weak". I > think I now know why. My secondary Q is only 36. That works out to a > secondary AC resistance of about 3300 ohms!! R = 2 x pi x F x L / Q > > > Terry Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Sat, 31 Aug 2002 12:14:43 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Sat, 31 Aug 2002 11:56:57 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: Re: OLTC update - Poor seconadry Q X-Mailing-List: archive/latest/1781 X-Loop: tesla@pupman.com Original poster: "Terry Fritz" Hi Bert, First thing I tried. It made no difference. Apparently the low Q is something with just the secondary/toroid. I will take off the toroid and investigate more... Cheers, Terry At 07:49 AM 8/31/2002 -0500, you wrote: >Hi Terry, > >I'd bet if you remove the secondary from the primary and re-measure it >you'll see a Q more like 200. The primary "gap" is conducting on >alternate half cycles, sapping energy from your secondary and lowering >the effective Q. > >Best regards, > >-- Bert -- >-- >Bert Hickman >Stoneridge Engineering >"Electromagically" (TM) Shrunken Coins! >http://www.teslamania.com > >Tesla list wrote: >> >> Original poster: "Terry Fritz" >> >> Hi All, >> >> I have adjusted my coil as best I can but the output still seems "weak". I >> think I now know why. My secondary Q is only 36. That works out to a >> secondary AC resistance of about 3300 ohms!! R = 2 x pi x F x L / Q >> > >> >> Terry > Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Sat, 31 Aug 2002 12:20:53 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Sat, 31 Aug 2002 11:59:05 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: Re: OLTC update - Poor seconadry Q X-Mailing-List: archive/latest/1787 X-Loop: tesla@pupman.com Original poster: "by way of Terry Fritz " Jimmy, My equation is reasonably accurate at around 300 watts. Here's some sample tests from 6/8/99. watts toroid predicted length actual spark length 280 3" x 10" 29" 27" 280 4" x 13" 29" 27" I didn't need to test a lot of different coils because my equation is not for the average coil, but only for efficient coils. John > > can you > feel the secondary heating? also weak compared to other 300 watt coils you > have > made or seen or are you comparing it to johns formula for input power and > park > length? the formula might not be accurate at low powers, i doubt he looked at > alot of 300 watt coils when making the formula. Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Sat, 31 Aug 2002 12:18:10 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Sat, 31 Aug 2002 12:00:39 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: Re: OLTC update - Poor seconadry Q X-Mailing-List: archive/latest/1791 X-Loop: tesla@pupman.com Original poster: "Antonio Carlos M. de Queiroz by way of Terry Fritz " Tesla list wrote: > > Original poster: "jimmy hynes by way of Terry Fritz " > > how do you know the q is so bad? did you measure it or calculate it? can you > feel the secondary heating? also weak compared to other 300 watt coils you have > made or seen or are you comparing it to johns formula for input power and park > length? the formula might not be accurate at low powers, i doubt he looked at > alot of 300 watt coils when making the formula. The formula appears to work well even with powers below 1 Watt. > > Just to give an idea of how bad this is... I am pumping and quenching 317 > > watts into the secondary system. 53 watts is going to streamers and a > > stunning 264 watts is going into heating up the secondary!!! > > > > So 83 percent of the power is "lost" :-(( > > > > Some notes are at: > > > > http://hot-streamer.com/temp/OLTCnotes.txt > > > > The entries at the last tell of the Q=36 case. Q=36 is not so bad. Most of the input energy is being transferred to the secondary. With k=0.2195 (mode 4,5) my calculations show that the voltage gain reaches 947, with the ideal maximum being 1089. About 76% of the input energy is reaching the secondary capacitance. Distributing the secondary capacitance of 36 pF as 18 pF for the self-capacitance of the secondary and 18 pF for the terminal, 38% of the input energy should be immediately available. > > So... I don't k! now if it is the SonoTube, surroundings, proximity effects, > > plastic wrap coating... Have to test some things... A small chance it > > could be the anti-parallel diodes... Your coil is performing as expected for a coil with a lot of relatively thin wire. I see the same happen in the coil that I used for my transformerless system, with the effective resistance being about 6 times the expected value considering skin depth alone. I think that proximity effects in the windings are the main reason for the large increase in the effective resistance. I would suspect also of the wrapping, that is an "untested technology". Air trapped between the layers may be getting ionized, and may be dissipating some energy. Antonio Carlos M. de Queiroz Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Sat, 31 Aug 2002 12:55:49 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Sat, 31 Aug 2002 12:51:24 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: Re: OLTC update - Poor seconadry Q X-Mailing-List: archive/latest/1796 X-Loop: tesla@pupman.com Original poster: "jimmy hynes by way of Terry Fritz " that was another question i was going to ask. when you say efficient coils do you mean it is really tough to beat the predicted lengt? or just a little above average? out of 100 randomly selected coils, how many would meet or beat the prediced length? also what is that more complicated formula that you didnt post on your page? Tesla list > > wrote: > Original poster: "by way of Terry Fritz " > > Jimmy, > > My equation is reasonably accurate at around 300 watts. > Here's some sample tests from 6/8/99. > > watts toroid predicted length actual spark length > 280 3" x 10" 29" 27" > 280 4" x 13" 29" 27" > > I didn't need to test a lot of different coils because my > equation is not for the average coil, but only for efficient > coils. > > John > > > > > > > can you > > feel the secondary heating? also weak compared to other 300 watt coils you > > have > > made or seen or are you comparing it to johns formula for input power and > > park > > length? the formula might not be accurate at low powers, i doubt he looked > at > > alot of 300 watt coils when making the formula. > > > > > > > > > > > > JImmy > > > > Do You Yahoo!? > Yahoo! > Finance - Get real-time stock quotes Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Sat, 31 Aug 2002 13:30:10 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Sat, 31 Aug 2002 13:27:00 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: Re: OLTC update - Poor seconadry Q X-Mailing-List: archive/latest/1800 X-Loop: tesla@pupman.com Original poster: "Terry Fritz" Hi Antonio, At 10:37 AM 8/31/2002 -0300, you wrote: ................. > >Q=36 is not so bad. Most of the input energy is being transferred to >the secondary. With k=0.2195 (mode 4,5) my calculations show that >the voltage gain reaches 947, with the ideal maximum being 1089. >About 76% of the input energy is reaching the secondary capacitance. >Distributing the secondary capacitance of 36 pF as 18 pF for the >self-capacitance of the secondary and 18 pF for the terminal, >38% of the input energy should be immediately available. Although, MicroSim is pretty "unverified" for subtle streamer behavior, it is saying that the instantaneous power to the streamer and to heating the coil looks like this: http://hot-streamer.com/temp/OLTC08-31-01.gif The red is the secondary heating power and the green is the streamer power. However, if one looks at the voltage across a 3300 ohm series resistor in the secondary and the streamer voltage, the loss looks small: http://hot-streamer.com/temp/OLTC08-31-02.gif I wander if I initially have the power but there just is not enough there to keep the streamer going. The sparks are more brush like too suggesting that is the case. Secondary loss, streamer impedance, and.... Is one of those areas that is not terribly well understood. Conventional coils seem to have just found the sweet spot but this coil seems to have found a "bad" spot. We'll probably learn a lot before this is over :-)) > >> > So... I don't k! now if it is the SonoTube, surroundings, proximity >effects, >> > plastic wrap coating... Have to test some things... A small chance it >> > could be the anti-parallel diodes... > >Your coil is performing as expected for a coil with a lot of relatively >thin wire. I see the same happen in the coil that I used for my >transformerless system, with the effective resistance being about 6 >times >the expected value considering skin depth alone. Mine is 6X too and Paul got a Q of 45 for the coil. Has program can predict these effects to a reasonable degree. >I think that proximity >effects in the windings are the main reason for the large increase in >the effective resistance. I would suspect also of the wrapping, that >is an "untested technology". Air trapped between the layers may be >getting ionized, and may be dissipating some energy. Good point! I may have made a giant corona machine there. But I measured the Q at low power (signal generator) too. But corona could certainly be a big factor at the high voltage... Time to get back into lab to investigate it all ;-)) Cheers, Terry > >Antonio Carlos M. de Queiroz > > Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Sat, 31 Aug 2002 22:14:00 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Sat, 31 Aug 2002 22:12:09 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: Re: OLTC update - Poor seconadry Q X-Mailing-List: archive/latest/1831 X-Loop: tesla@pupman.com Original poster: "Bert Hickman by way of Terry Fritz " Hi Terry, Yeah, I figured that was too easy! :^) After reading some of the later posts, I "plugged in" your secondary's parameters into a spreadsheet I use for coil design. The impact of skin effect and coil resistance drops the loaded Q to about 90. Assuming that proximity effects for your closewound coil are of the same magnitude as for skin effect, the Q would drop down to the mid 40's (even assuming a "perfect" ground to the base of the resonator). Throw in a bit ground impedance and add some more losses from the Sonotube, and the measured value is certainly in the right ballpark. Bummer! Sounds like you'll need a significantly larger diameter coilform wound with larger diameter magnet wire to get Q up to a decent level. For example, using a 30" x 6.5" toroid atop a 20" coilform wound with 35" of #22 AWG (~1230 turns relatively closewound) should give you about the same Fo of 38 kHz. However, Q should be closer to ~70 - 80. Like the car ad says, wider is [probably] better.. :^) However, a 30 pound system it ain't (any more...). Best regards, -- Bert -- -- Bert Hickman Stoneridge Engineering "Electromagically" (TM) Shrunken Coins! http://www.teslamania.com Tesla list wrote: > > Original poster: "Terry Fritz" > > Hi Bert, > > First thing I tried. It made no difference. Apparently the low Q is > something with just the secondary/toroid. I will take off the toroid and > investigate more... > > Cheers, > > Terry > > At 07:49 AM 8/31/2002 -0500, you wrote: > >Hi Terry, > > > >I'd bet if you remove the secondary from the primary and re-measure it > >you'll see a Q more like 200. The primary "gap" is conducting on > >alternate half cycles, sapping energy from your secondary and lowering > >the effective Q. > > > >Best regards, > > > >-- Bert -- > >-- > >Bert Hickman > >Stoneridge Engineering > >"Electromagically" (TM) Shrunken Coins! > >http://www.teslamania.com > > > >Tesla list wrote: > >> > >> Original poster: "Terry Fritz" > >> > >> Hi All, > >> > >> I have adjusted my coil as best I can but the output still seems "weak". I > >> think I now know why. My secondary Q is only 36. That works out to a > >> secondary AC resistance of about 3300 ohms!! R = 2 x pi x F x L / Q > >> > > > >> > >> Terry > > Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Sat, 31 Aug 2002 23:13:06 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Sat, 31 Aug 2002 23:09:14 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: Re: OLTC update - Poor seconadry Q X-Mailing-List: archive/latest/1832 X-Loop: tesla@pupman.com Original poster: "Terry Fritz" Hi Bert, At 11:08 PM 8/31/2002 -0500, you wrote: >Hi Terry, > >Yeah, I figured that was too easy! :^) > >After reading some of the later posts, I "plugged in" your secondary's >parameters into a spreadsheet I use for coil design. The impact of skin >effect and coil resistance drops the loaded Q to about 90. Assuming that >proximity effects for your closewound coil are of the same magnitude as >for skin effect, the Q would drop down to the mid 40's (even assuming a >"perfect" ground to the base of the resonator). Throw in a bit ground >impedance and add some more losses from the Sonotube, and the measured >value is certainly in the right ballpark. Bummer! Paul's program cam up with a Q of 45. I sent him a scope trace in digital form and he got: -------------- ""Couldn't resist a quick look, your TEK00001.CSV gives PK FREQ kHz (Error +/-) Q FACTOR (Error +/-) LEVEL 1 33.569 (0.01%,5Hz) 18.09 (3.95%, 0.7) -3.3dB 1/4 wave 2 43.335 (0.01%,6Hz) 20.84 (3.32%, 0.7) -2.6dB 1/4 wave 3 119.109 (0.01%,16Hz) 22.17 (6.64%, 1.5) -19.7dB 3/4 wave 4 181.202 (0.01%,25Hz) 15.10 (31.58%, 4.8) -24.4dB 5/4 wave The measured Q of the secondary ringing alone is 45, which is reasonable. But when the primary is involved, the overall Q is being halved."" -------------- I also sent him some primary only data. The Q of the primary looks like about 35 at low power. It gets better at higher power. -------------- ""I ran the primary alone as shown: http://hot-streamer.com/temp/OLTC08-31-06.jpg I ran at 5 input voltages of 20,40,60,80, and 100 volts as read on the meter. On 120 VAC that can go up to 150 volts and at 240 VAC in it goes up to 300 volts. So I still have 3x the voltage to go. I didn't go higher here since I am not sure where the "power" is going? The files are at: http://hot-streamer.com/temp/OLTC/8-31PriD-1/ These are basically the voltage across the coil. I don't have a trustworthy way of measuring primary current. I was thinking just a loop at the bottom of the coil (like on the base) that went across a resistor and was calibrated... But never have been able to get that going (time). I would expect the Q to rise as the input voltages goes up in keeping with the way the IGBTs should handle loss. I would be interested in how the Q changes with increasing voltage."" --------------- So it looks like I am bleeding Q all over the place. I plugged the Q values into MicroSim and got 11mARMS into the arc for an un-astounding streamer power of 26 watts With 10 inch streamers according to John's formula. That is just about what I am seeing at this level. I do have 10X the power to go, but I am holding off till I better understand things. If I pump 1000 watts into the coil and 50 watts comes out... I 'really' want to know 'where' the rest is going! I expected this OLTC thing to be at the "bleeding edge" of technology :o)) However, the electronics and all went so smooth and it looks like the "interesting" part is in much more conventional areas of Tesla coil design that we do not understand very well. Primary Q, secondary Q, streamer impedance, power transfer to streamers, losses... All juicy subjects :o))) The OLTC is great for work in these areas since it seems to have hit a nice 'bad spot' where are current knowledge is weak. However, with it's simple low voltage primary circuits, it is very easy to probe and measure things! The areas were it raises question were 'next on the list' anyway ;-)) So it appears that the low Q SonoTube is a minor factor given the proximity effects and all. No use in trying a higher Q (like polypropylyne) secondary form. Probably needs a low Q secondary designed from the ground up for low Q losses. I expected low Q in the primary at these lower powers. Yeasterday's experiment that showed I could run 'big' current throught the IGBTs allows me a whole lot of freedom to 'crank this baby up'!! I am still amazed that as much goofing around and fiddling with this coil that I have done that nothing has failed. The basic machine seems to be solid and tough!! It seems very capable of delivering 5000 peak amp long ringdowns to a well coupled primary, even in it's 'first' form. I bet the Q of the primary will go up to like 75 at full power. The basic figures would then be... k=0.25, Ipeak=5000 amps, PriQ=75... You just 'have' to be able to make a Tesla coil from there ;O))) Cheers, Terry > >Sounds like you'll need a significantly larger diameter coilform wound >with larger diameter magnet wire to get Q up to a decent level. For >example, using a 30" x 6.5" toroid atop a 20" coilform wound with 35" of >#22 AWG (~1230 turns relatively closewound) should give you about the >same Fo of 38 kHz. However, Q should be closer to ~70 - 80. Like the car >ad says, wider is [probably] better.. :^) > >However, a 30 pound system it ain't (any more...). > >Best regards, > >-- Bert -- >-- >Bert Hickman >Stoneridge Engineering >"Electromagically" (TM) Shrunken Coins! >http://www.teslamania.com > > Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Sun, 1 Sep 2002 08:23:40 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Sun, 01 Sep 2002 08:18:19 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: Re: OLTC update - Poor seconadry Q X-Mailing-List: archive/latest/1838 X-Loop: tesla@pupman.com Original poster: "Antonio Carlos M. de Queiroz by way of Terry Fritz " Tesla list wrote: > > Original poster: "Terry Fritz" > Although, MicroSim is pretty "unverified" for subtle streamer behavior, it > is saying that the instantaneous power to the streamer and to heating the > coil looks like this: > > http://hot-streamer.com/temp/OLTC08-31-01.gif Ok, for your model. > The red is the secondary heating power and the green is the streamer power. > > However, if one looks at the voltage across a 3300 ohm series resistor in > the secondary and the streamer voltage, the loss looks small: > > http://hot-streamer.com/temp/OLTC08-31-02.gif Note that what appears over the resistor in one cycle, peak to peak, is approximately what is missing in the next voltage peak. I didn't check if the theoretical rule is this, but it's something like this. > I wander if I initially have the power but there just is not enough there > to keep the streamer going. The sparks are more brush like too suggesting > that is the case. Really, if streamer formation depends on many cycles with the energy trapped in the secondary system, this may be a problem. I don't remember seing a study about this in this list. With Q=36 and 3300 Ohms of series resistance, the equivalent parallel resistance is 36*3300 = 118800, and the streamer with 220 kOhms is really not contributing much for the energy drain. > Secondary loss, streamer impedance, and.... Is one of those areas that is > not terribly well understood. Conventional coils seem to have just found > the sweet spot but this coil seems to have found a "bad" spot. We'll > probably learn a lot before this is over :-)) A question is: What is important for streamer formation? High Q secondary or a lot of energy available directly from the terminal? For sparks to ground, the later is the answer, but for streamers it's not clear. > Mine is 6X too and Paul got a Q of 45 for the coil. Has program can > predict these effects to a reasonable degree. So, proximity is really the problem. But to space-wind 0.5 H of inductance would be a big problem... > Good point! I may have made a giant corona machine there. But I measured > the Q at low power (signal generator) too. But corona could certainly be a > big factor at the high voltage... You could make an experiment, wrapping a coil that has known characteristics and observing if its Q decreases. Antonio Carlos M. de Queiroz Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Sun, 1 Sep 2002 20:02:15 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Sun, 01 Sep 2002 19:46:26 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: Re: OLTC update - Poor seconadry Q X-Mailing-List: archive/latest/1847 X-Loop: tesla@pupman.com Original poster: "by way of Terry Fritz " Jimmy, The predicted length can be beaten, esp at higher powers. The more complex formula takes this into account, and gives a somewhat longer spark length prediction for larger coils. This new formula also takes break rate into account. I used various math roots to create the needed "skewing" of the results. I used whole number roots rather than non-whole number roots for simplicity, although non-whole number roots would give better accuracy. Actually someone eventually mailed me a formula they made along the same lines as mine, where they used non-whole number roots and it gave better results. I must admit that I just don't have enough data to know what breakrate results are due to variations in coil design by various builders, and what part of the results stems from actual spark growth characteristics due to breakrate differences. The more complex formula follows, but I must admit I don't trust it all that much, and as I mentioned, it would benefit from the use of non-whole number roots. Spark length inches = [(3.9*16th.root watts)*sqrt watts] / 4th.root BPS (for 120 - 480 bps) (watts are wallplug watts) I would estimate that the lengths predicted by my formula are far above the average spark length, especially for smaller coils. For example, many 12/30 NST powered coils give only about an 18" spark or so, which falls far short of the 42" that my formula predicts, and which my old research coil achieved. Many small coils are limited by; poor spark gaps, too small toroids, too few primary and secondary turns, etc. It would be really tough to beat the 42" spark length for a 12/30 NST (600 watts), by any significant amount I think. Actually, I've never heard of anyone beating that result. At higher powers, many well designed coils meet or slightly exceed the formula's predicted spark lengths. John > > that was another question i was going to ask. when you say efficient coils do > you mean it is really tough to beat the predicted lengt? or just a little > above > average? out of 100 randomly selected coils, how many would meet or beat the > prediced length? also what is that more complicated formula that you didnt > post > on your page? > > Tesla list > > > > wrote: > > Original poster: "by way of Terry Fritz " > > > > Jimmy, > > > > My equation is reasonably accurate at around 300 watts. > > Here's some sample tests from 6/8/99. > > > > watts toroid predicted length actual spark length > > 280 3" x 10" 29" 27" > > 280 4" x 13" 29" 27" > > > > I didn't need to test a lot of different coils because my > > equation is not for the average coil, but only for efficient > > coils. > > > > John Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Sun, 1 Sep 2002 20:10:34 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Sun, 01 Sep 2002 19:47:19 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: Re: OLTC update - Poor seconadry Q X-Mailing-List: archive/latest/1850 X-Loop: tesla@pupman.com Original poster: "by way of Terry Fritz " In a message dated 9/1/02 10:22:53 AM Eastern Daylight Time, tesla@pupman.com writes: > > Really, if streamer formation depends on many cycles with the energy > trapped in the secondary system, this may be a problem. I don't > remember seing a study about this in this list. With Q=36 and 3300 > Ohms of series resistance, the equivalent parallel resistance is > 36*3300 = 118800, and the streamer with 220 kOhms is really not > contributing much for the energy drain. Antonio, all, I remember in my earlier coiling days, I built a tube coil and made a large secondary 14" diameter x 26" long with three sizes of wire, 22 awg, 24 awg and 28 awg, wound onto a sonotube cardboard form, and coated with water-based poly. What a rotten coil ! The sparks were only 19" long, instead of the 24" I obtained when using a more normal sized secondary. It didn't help that I used coax cable braid as the primary :( (!) That secondary got hot at the top ! I guess all the water from the water-based poly went into the cardboard. There may have been other bad stuff in the cardboard sonotube also. > > > Secondary loss, streamer impedance, and.... Is one of those areas that is > > not terribly well understood. Conventional coils seem to have just found > > the sweet spot but this coil seems to have found a "bad" spot. We'll > > probably learn a lot before this is over :-)) > > A question is: What is important for streamer formation? High Q > secondary or a lot of energy available directly from the terminal? > For sparks to ground, the later is the answer, but for streamers it's > not clear. And do successive beat transfers (poor quench) within a bang contribute much to the spark length, or is it more the initial energy transfer to the secondary that is most important in establishing the spark length? Perhaps the successive beats help to keep the channel ionized, and thus assist the next growth spurt in the next bang.... even if the successive beat transfers within a bang do not directly contribute to spark growth. I realize Bert H. has suggested that successive beats within a bang may directly contribute to spark growth. Another way of saying this is: Does the spark length depend more on the total power delivered to the streamer, or does the manner and timing of the delivery matter more. This would involves such aspects as; number of beat transfers in a bang, BPS, toroid energy storage, etc. In other words the still- unknown aspects of spark growth in air in Tesla coils. John Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Sun, 1 Sep 2002 20:02:13 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Sun, 01 Sep 2002 19:47:53 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: Re: OLTC update - Poor seconadry Q X-Mailing-List: archive/latest/1851 X-Loop: tesla@pupman.com Original poster: "Kurt Schraner by way of Terry Fritz " Hi Terry, with highest interest I follow the development of the OLTC from the beginning, just by lurking. Great what you make happen there, letting us take part! Regarding the secondary Q problem, just thinking out loud: Might we benefit from something, along the lines of Jeff Behary's rediscovery of Tesla's multilayer pancake secondary coils ? Jeff is taking reference to Tesla's Patent No.593,138; 2.Nov.1987 which is not currently at my disposition. Jeff's development may be clicked at his website: http://www.electrotherapymuseum.com ...more specifically at: http://electrotherapymuseum.com/Pancake1/ ...and for the coil winding process: http://www.electrotherapymuseum.com/Details/index.htm While there are probably better ones, here is a formula for short multilayer pancake air coils: L[mH] = K*N^2*(Da/2)*10^-5 with Da = outer diameter [cm] Di = inner diameter [cm] x = Di/Da; 0.1 < x < 0.9 length << Da (short coil!) K=7.1801*x^3 - 5.6587*x^2 + 3.748*x + 0.5068 My hope is, getting better Q high inductance coils, while keeping size and weight within a reasonable range, relative to the OLTC needs. The winding experience with old style induction coils also might provide interesting alternatives to a pure solenoid secondary. Vacuum impregnation might be needed, but also is easier with smaller coils. Cheers, Kurt Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Sun, 1 Sep 2002 20:14:03 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Sun, 01 Sep 2002 19:50:33 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: Re: OLTC update - Poor seconadry Q X-Mailing-List: archive/latest/1858 X-Loop: tesla@pupman.com Original poster: "Malcolm Watts by way of Terry Fritz " Hi Terry, On 30 Aug 2002, at 15:21, Tesla list wrote: > Original poster: "Terry Fritz" > > Hi All, > > I have adjusted my coil as best I can but the output still seems "weak". I > think I now know why. My secondary Q is only 36. That works out to a > secondary AC resistance of about 3300 ohms!! R = 2 x pi x F x L / Q Thankyou for confirming my suspicions. Regards, malcolm > Paul - The pinger file is here if your are interested. > > http://hot-streamer.com/temp/OLTCsec.CSV > > The waveform is at: > > http://hot-streamer.com/temp/OLTC08-30-01.gif > > Just to give an idea of how bad this is... I am pumping and quenching 317 > watts into the secondary system. 53 watts is going to streamers and a > stunning 264 watts is going into heating up the secondary!!! > > So 83 percent of the power is "lost" :-(( > > Some notes are at: > > http://hot-streamer.com/temp/OLTCnotes.txt > > The entries at the last tell of the Q=36 case. > > So... I don't know if it is the SonoTube, surroundings, proximity effects, > plastic wrap coating... Have to test some things... A small chance it > could be the anti-parallel diodes... > > Of course, this is not a problem with the basic OLTC technology, that works > great!, but rather an age old problem of making secondaries without really > low Q... > > Of course, ideas on how I can fix this are more than welcome :-)) > > The specs of the secondary system are: > > L = 480mH > Wire gauge = #28 > Turns = 2760 > Winding length = 41 inches > Diameter = 10.75 inches > Q = 36.0 :-p > Fo = 38.2kHz > Csec = 35pF > > Torroid 24" diameter x 6.5" cord > Center or toroid 3.5 inches above last secondary turn. > > Cheers, > > Terry > > > > > Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Sun, 1 Sep 2002 20:13:02 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Sun, 01 Sep 2002 19:51:02 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: Re: OLTC update - Poor seconadry Q X-Mailing-List: archive/latest/1857 X-Loop: tesla@pupman.com Original poster: "Malcolm Watts by way of Terry Fritz " Hi Jimmy, On 30 Aug 2002, at 20:54, Tesla list wrote: > Original poster: "jimmy hynes by way of Terry Fritz " > > > how do you know the q is so bad? did you measure it or calculate it? can you > feel the secondary heating? also weak compared to other 300 watt coils you have > made or seen or are you comparing it to johns formula for input power and park > length? the formula might not be accurate at low powers, i doubt he looked at > alot of 300 watt coils when making the formula. my calculations said the q > should be around 200. i used the javatc to get a guess at the resistance. i > dont trust my calculations too much because i didnt find the equations. i > derived the equation myself, and i make alot of mistakes. I could see it just by looking at the oscillogram of the secondary ringing alone. A decent secondary rings for ages. It basically stands to reason. If you use thin wire and a long length of it in a relatively small coil, the AC losses will be, to use the Corum's words, incredible. Been there, done that. Obviously, the wire is far smaller than even a single skin depth at the frequency Terry is running and the proximity losses make it even worse. Regards, Malcolm > Tesla list wrote: > > > > Original poster: "Terry Fritz" > > > > Hi All, > > > > I have adjusted my coil as best I can but the output still seems "weak". I > > think I now know why. My secondary Q is only 36. That works out to a > > secondary AC resistance of about 3300 ohms!! R = 2 x pi x F x L / Q > > > > Paul - The pinger file is here if your are interested. > > > > http://hot-streamer.com/temp/OLTCsec.CSV > > > > The waveform is at: > > > > http://hot-streamer.com/temp/OLTC08-30-01.gif > > > > Just to give an idea of how bad this is... I am pumping and quenching 317 > > watts into the secondary system. 53 watts is going to streamers and a > > stunning 264 watts is going into heating up the secondary!!! > > > > So 83 percent of the power is "lost" :-(( > > > > Some notes are at: > > > > http://hot-streamer.com/temp/OLTCnotes.txt > > > > The entries at the last tell of the Q=36 case. > > > > So... I don't k! now if it is the SonoTube, surroundings, proximity effects, > > plastic wrap coating... Have to test some things... A small chance it > > could be the anti-parallel diodes... > > > > Of course, this is not a problem with the basic OLTC technology, that works > > great!, but rather an age old problem of making secondaries without really > > low Q... > > > > Of course, ideas on how I can fix this are more than welcome :-)) > > > > The specs of the secondary system are: > > > > L = 480mH > > Wire gauge = #28 > > Turns = 2760 > > Winding length = 41 inches > > Diameter = 10.75 inches > > Q = 36.0 :-p > > Fo = 38.2kHz > > Csec = 35pF > > > > Torroid 24" diameter x 6.5" cord > > Center or toroid 3.5 inches above last secondary turn. > > > > Cheers, > > > > Terry > > > > > > > > JImmy > Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Sun, 1 Sep 2002 20:02:14 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Sun, 01 Sep 2002 19:51:25 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: Re: OLTC update - Poor seconadry Q X-Mailing-List: archive/latest/1859 X-Loop: tesla@pupman.com Original poster: "Malcolm Watts by way of Terry Fritz " Hi Bart, On 30 Aug 2002, at 21:59, Tesla list wrote: > Original poster: "Barton B. Anderson by way of Terry Fritz " > > Terry, > > Tesla list wrote: > > > Original poster: "Terry Fritz" > > > > So... I don't know if it is the SonoTube, surroundings, proximity effects, > > plastic wrap coating... Have to test some things... A small chance it > > could be the anti-parallel diodes... > > I think none of the above, but rather the secondary itself. I would bet the Q > of the secondary by itself is pretty low. > > > Of course, ideas on how I can fix this are more than welcome :-)) > > Rewind a secondary with less turns and larger wire. Fres will tripple (not sure > how tied into 0.47uF you are with the IGBT current). Of course, with all the > work you put into this project already, I hope it's something else. That is exactly the problem. The large Cp is causing all sorts of design havoc with the secondary which is really far too small to give low losses at 30-something kHz. Regards, Malcolm > BTW, if you were to model the secondary in JavaTC (since it was mentioned in > another post), here are the input parameters for your coil: > > Sec Diam = 10.75 > Sec Length = 41 > Bare Wire Diam = 0.0126 > Insulation = 0.001 > Spacing = 0.000255 > Toroid Major = 24 > Toroid Minor = 6.5 > Sphere Diam = 0 > Top Load Reduction = 36.3 > > Here are some of the main outputs JavaTC identifies: > DC Resistance = 507.53 ohms > Inductance = 480.13 mH > Self Fres = 52.4 kHz > Skin depth = 0.014 inch > Loaded Fres = 38.21 kHz > Total Capacitance = 36.14pF > > Take care, > Bart > > http://www.classictesla.com/java/javatc.html > or > http://www.classictesla.com/java/javatc92.html > The bottom link is beta version 9.2 > > > > > Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Mon, 2 Sep 2002 08:19:26 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Mon, 02 Sep 2002 08:10:17 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: Re:OLTC update - Poor seconadry Q X-Mailing-List: archive/latest/1873 X-Loop: tesla@pupman.com Original poster: "Greg Leyh by way of Terry Fritz " Hi John, That's an interesting equation... I'd like to see it with the non-whole number roots. Did you arrive at this equation empirically by matching it to data points? The 120" secondary out at Jim Heagy's place in the shipyard beats the equation by about 15%, and Electrum falls short of the equation, also by about 15%. This could be explained by the different engineering approaches of the two coils. Electrum is conservatively designed, and has a few 'artistic compromises' in the engineering solution as well. The shipyard coil enjoys a more optimal top load capacitance and primary Q, and is run 'balls out', in terms of design conservatism. Are there many data points that fall in a nice distribution around this curve? It would be interesting to find how far out this curve could be reasonably extrapolated. Inserting 240BPS and 3.6MW into the equation yields 402ft... which is more than twice the spark length performance required per tower. On the other hand it's probably good to have some reserve capacity, especially when it's not practical to field rework many of the critical coil parameters. >Original poster: > >[snip] >The more complex formula follows, but I must admit I don't >trust it all that much, and as I mentioned, it would benefit from >the use of non-whole number roots. > >Spark length inches = > [(3.9*16th.root watts)*sqrt watts] / 4th.root BPS > >(for 120 - 480 bps) >(watts are wallplug watts) > >I would estimate that the lengths predicted by my formula are >far above the average spark length, especially for smaller coils. >For example, many 12/30 NST powered coils give only about >an 18" spark or so, which falls far short of the 42" that my >formula predicts, and which my old research coil achieved. >Many small coils are limited by; poor spark gaps, too small >toroids, too few primary and secondary turns, etc. It would >be really tough to beat the 42" spark length for a 12/30 NST >(600 watts), by any significant amount I think. Actually, I've >never heard of anyone beating that result. > >At higher powers, many well designed coils meet or slightly >exceed the formula's predicted spark lengths. > >John Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Mon, 2 Sep 2002 12:50:44 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Mon, 02 Sep 2002 12:29:41 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: Re: OLTC update - Poor seconadry Q X-Mailing-List: archive/latest/1888 X-Loop: tesla@pupman.com Original poster: "by way of Terry Fritz " In a message dated 9/2/02 10:15:50 AM Eastern Daylight Time, tesla@pupman.com writes: > > Original poster: "Greg Leyh by way of Terry Fritz " > > > Hi John, > > That's an interesting equation... I'd like to > see it with the non-whole number roots. Hi Greg, I don't think I have the non-whole number root equation handy. I think it's locked up in a defunct computer. Maybe the person who sent it to me will see this if they're still on the list. I can't remember who it was. > > Did you arrive at this equation empirically > by matching it to data points? Yes, it's just empirical, just a guide. > > The 120" secondary out at Jim Heagy's place > in the shipyard beats the equation by about > 15%, and Electrum falls short of the equation, > > also by about 15%. Oh, of the new equation. Still, I thought Electrum was quite efficient at the lower breakrates. I must have misunderstood some of your old e-mails. I'd appreciate it if you could post a small table of breakrate vs. spark length for the Electrum. This could be explained by > > the different engineering approaches of the two > coils. Electrum is conservatively designed, and > has a few 'artistic compromises' in the engineering > solution as well. The shipyard coil enjoys a more > optimal top load capacitance and primary Q, and is > run 'balls out', in terms of design conservatism. Understood. > > Are there many data points that fall in a nice > distribution around this curve? It would be > interesting to find how far out this curve > could be reasonably extrapolated. The data points I've seen fall nicely on the new curve, but may be leaving the curve at higher powers. I've ignored inefficient coil which may be power-arcing, or have other obvious design flaws. I have no idea how far the curve can be reasonably extrapolated. I assumed the limit is the limit you have spoken about in the past. > > Inserting 240BPS and 3.6MW into the equation > yields 402ft... which is more than twice the > spark length performance required per tower. > On the other hand it's probably good to have > some reserve capacity, especially when it's > not practical to field rework many of the > critical coil parameters. Sounds good. The new equation is somewhat too optimistic at the higher breakrates I think, and may be too optimistic as the power rises. It needs the non-whole number roots to be more accurate. John Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Sun, 18 Aug 2002 23:20:56 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Sun, 18 Aug 2002 23:14:16 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: OLTC Update - Primary circuit resistance. X-Mailing-List: archive/latest/1277 X-Loop: tesla@pupman.com Original poster: "Terry Fritz" Hi All, > >Here is the primary voltage and drive signal at about 50 volts input (all I >can reasonably do right now): > > http://hot-streamer.com/temp/OLTC08-18-07.gif > >I will have to figure out the loss and divide it by ten for the 500 volt >case where the coil will actually run. The losses of IGBTs or more or less >proportional to current, but the power is proportional to current squared. >So as you increase the current (drive voltage), efficiency of the coil >increases. So right now, the all important primary loss looks fine. > I calculated and measured and estimated the full power (550V) resistance of the primary circuit. It came out to a stunning 0.0006 ohms!! 600uOhms. That is well over 10X what the coil needed ;-)) With such tiny primary circuit resistances and associated very low losses, many other low voltage Tesla coil schemes are possible too! However, the current is "high"! In my 50 volt testing tonight, I must have been hitting 500 amps peak! It may turn into a 120VAC coil instead of a 240VAC coil... Or, get rid of that charging reactor... Definitely must be very careful of running without a secondary or a miss-tuned secondary. MicroSim says I could hit 5000 amps in a nice slow ringdown. That would destroy the IGBTs... Even in the full coil MicroSim warns of 6000! Amps now.... This changes things a bit, but it is wonderful in the long run :-))) As odd as it sounds, I may have to run my coil off 120 VAC without resonant charging (but at higher break rates?)... An even simpler coil. Or add primary loss. In the first stage, I may have to run it on a variac just to "reduce" the voltage! I may be able to pump up the break rate, but hat means more currents that I was not expecting... Many complexities are added here, but they are good ones ;-)) I seem to have far more power than I expected :o)) The whole idea was to pump 2000 amps at about 30kHz through a primary coil coupled to the secondary. I may have vastly overdone it ;-))) With only 0.0006 ohms of primary resistance, I could use a 1.5 volt battery :o))) Cheers, Terry Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Mon, 19 Aug 2002 08:36:52 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Mon, 19 Aug 2002 08:26:41 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: Re: OLTC Update - Primary circuit resistance. X-Mailing-List: archive/latest/1287 X-Loop: tesla@pupman.com Original poster: "Eddie Burwell by way of Terry Fritz " At 11:14 PM 8/18/02 -0600, you wrote: >Original poster: "Terry Fritz" >However, the current is "high"! In my 50 volt testing tonight, I must have >been hitting 500 amps peak! It may turn into a 120VAC coil instead of a >240VAC coil... Or, get rid of that charging reactor... Definitely must be >very careful of running without a secondary or a miss-tuned secondary. >MicroSim says I could hit 5000 amps in a nice slow ringdown. That would >destroy the IGBTs... > >Even in the full coil MicroSim warns of 6000! Amps now.... > >This changes things a bit, but it is wonderful in the long run :-))) As >odd as it sounds, I may have to run my coil off 120 VAC without resonant >charging (but at higher break rates?)... An even simpler coil. Or add >primary loss. In the first stage, I may have to run it on a variac just to >"reduce" the voltage! I may be able to pump up the break rate, but hat >means more currents that I was not expecting... Many complexities are >added here, but they are good ones ;-)) > >I seem to have far more power than I expected :o)) > >The whole idea was to pump 2000 amps at about 30kHz through a primary coil >coupled to the secondary. I may have vastly overdone it ;-))) With only >0.0006 ohms of primary resistance, I could use a 1.5 volt battery :o))) > >Cheers, > > Terry > Terry, One thing I have contemplated but have not tested is I believe that if you push an IGBT past it's maximum current ratings it may not necessarily die. I think the reason the manufacturers place the maximum peak current rating where they do is that if the current exceeds a certain point the IGBT latches on like a SCR. In other words the ratings are spec'ed to maintain gate control. The important thing for semiconductor health is die temperature. We could start out by assuming that the pulse is so brief and intense that the thermal conductivity of the package can't remove the heat generated during the actual pulse. If that is the case, any energy dissipated in the device during the pulse will go directly to heating the die. We can measure the die and approximate it's mass. Using the specific heat of silicon we could then calculate the energy necessary to elevate the die temperature by some amount. After the pulse the die will cool down until it is hit with the next pulse. I have a feeling this approach should be valid especially since IGBTs don't have di/dt failure modes(at least for halfway sane levels of di/dt) like SCRs do. The main question is if there is some other failure mode that kicks in above Icm. If the IGBT latched on while the current was above Icm and the regained gate control below Icm the OLTC may seriously be in business. The other snag I can think of is that it's not just one pulse that the IGBT is dealing with, it's a sequence of decaying pulses. The first pulse will bump the die temp up the most. The last of the pulses as quenching is approached will probably be of little consequence as far as die heating is concerned. Perhaps it's time to destructively test some single devices under the heavy scrutiny of test equipment? Eddie Burwell Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Mon, 19 Aug 2002 11:57:06 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Mon, 19 Aug 2002 11:46:02 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: Re: OLTC Update - Primary circuit resistance. X-Mailing-List: archive/latest/1295 X-Loop: tesla@pupman.com Original poster: "Darren Freeman by way of Terry Fritz " Comments interspersed: At 11:56 PM 19/08/2002, you wrote: >Original poster: "Eddie Burwell by way of Terry Fritz >" > >At 11:14 PM 8/18/02 -0600, you wrote: > >Original poster: "Terry Fritz" > > >However, the current is "high"! In my 50 volt testing tonight, I must have > >been hitting 500 amps peak! It may turn into a 120VAC coil instead of a > >240VAC coil... Or, get rid of that charging reactor... Definitely must be > >very careful of running without a secondary or a miss-tuned secondary. > >MicroSim says I could hit 5000 amps in a nice slow ringdown. That would > >destroy the IGBTs... Something I've been worried about for a while =) > One thing I have contemplated but have not tested is I believe that if you >push an IGBT past it's maximum current ratings it may not necessarily die. I >think the reason the manufacturers place the maximum peak current rating >where they do is that if the current exceeds a certain point the IGBT >latches on like a SCR. In other words the ratings are spec'ed to maintain >gate control. > The important thing for semiconductor health is die temperature. We could >start out by assuming that the pulse is so brief and intense that the >thermal conductivity of the package can't remove the heat generated during >the actual pulse. If that is the case, any energy dissipated in the device >during the pulse will go directly to heating the die. We can measure the die >and approximate it's mass. Using the specific heat of silicon we could then >calculate the energy necessary to elevate the die temperature by some >amount. After the pulse the die will cool down until it is hit with the next >pulse. With BJTs and I suppose IGBTs as well, this doesn't work. What happens is the most conductive part of the die takes a little more current than the rest, so heating itself up a little hotter. With MOSFETs that would cause its conductivity to drop and reduce its heating, so the process is stabilising. But with a BJT the locally heated region becomes more conductive and the current rises, causing more heating and so on until the device is destroyed. At least it's what I've read, I never pushed insane currents through them before =) Check the Safe Operating Area of the devices and don't expect to push much past it for too many pulses - there should be a limit to what you can do even in a once off pulse. Don't count on thermal effects allowing stupidly high currents =) > I have a feeling this approach should be valid especially since IGBTs >don't have di/dt failure modes(at least for halfway sane levels of di/dt) >like SCRs do. The main question is if there is some other failure mode that >kicks in above Icm. If the IGBT latched on while the current was above Icm >and the regained gate control below Icm the OLTC may seriously be in >business. The other snag I can think of is that it's not just one pulse that >the IGBT is dealing with, it's a sequence of decaying pulses. The first >pulse will bump the die temp up the most. The last of the pulses as >quenching is approached will probably be of little consequence as far as die >heating is concerned. > >Perhaps it's time to destructively test some single devices under the heavy >scrutiny of test equipment? Probably a good idea if the plan is to go ahead!! >Eddie Burwell Have fun, Darren Freeman Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Mon, 19 Aug 2002 12:27:10 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Mon, 19 Aug 2002 12:21:56 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: Re: OLTC Update - Primary circuit resistance. X-Mailing-List: archive/latest/1296 X-Loop: tesla@pupman.com Original poster: "Terry Fritz" Hi All, Eddie mentions that the IGBTs may be able to take higher currents than rated. Darren disagreed since "spot heating" on the die may be a problem. Hard to say... At these points the data sheets and the manufacturers say "your on your own. Good luck! :o)) The "cheap" IGBTs don't use copper on silicon or any of that fancy stuff. Ones that do, appear very similar but are rated at 280 amps instead of 204. I would guess we are nearing the point that the conductors in the die will simply fuse. Spot heating may not be too bad since the die are running very cold. Like 30 C. So we have a lot of room for heating! A lot depends on how well the IGBT and package are made. IMHO International Rectifier is the best in the business there. We really just have to test them and find out... It will be interesting to see how much margin is really there. IR usually over rates CE voltage by about 100 volts and that is a known hard limit that we can't go over especially with our currents. Far far beyond any avalanche current rating! Marco mentions that I am running the gates at pretty high voltage (18V). IGBTs like these usually "break" at about 50 volts on the gate. No problem nearing the 20 volt spec there. The 2 9V batteries will quickly go down to about 16 volts. That is only 6 volts over the full 200 amps on spec and I am a little worried about noise getting on the gates too so more margin is nice. Shoot through from the Ccg capacitance is a concern and that is why I have 100 ohm gate resistors to slow the turn on way down compared to what it "could" be. Bert mentions "As previously mentioned, a possible downside is that, through transformer action, some of the secondary's energy will be extracted during secondary ringdown, resulting in partial recharging of the tank caps through the internal HexFRED diodes." The "theory" is: In order for the primary to take energy back from the secondary. The primary has to be "tuned". When the IGBT opens, it destroys the primary as a tuned circuit. Thus the primary will not be able to take back the energy. We will really just have to see what happens There. there is a "plan B" of two IGBTs in a CE-EC configuration. But we'll see if we even have to worry about it. Cheers, Terry Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Mon, 19 Aug 2002 17:43:47 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Mon, 19 Aug 2002 17:31:36 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: Re: OLTC Update - Primary circuit resistance. X-Mailing-List: archive/latest/1302 X-Loop: tesla@pupman.com Original poster: "Malcolm Watts by way of Terry Fritz " Hi Terry, On 19 Aug 2002, at 12:21, Tesla list wrote: > Original poster: "Terry Fritz" > > Hi All, > > Eddie mentions that the IGBTs may be able to take higher currents than > rated. Darren disagreed since "spot heating" on the die may be a problem. > Hard to say... At these points the data sheets and the manufacturers say > "your on your own. Good luck! :o)) The "cheap" IGBTs don't use copper on > silicon or any of that fancy stuff. Ones that do, appear very similar but > are rated at 280 amps instead of 204. I would guess we are nearing the > point that the conductors in the die will simply fuse. Spot heating may > not be too bad since the die are running very cold. Like 30 C. So we have > a lot of room for heating! A lot depends on how well the IGBT and package > are made. IMHO International Rectifier is the best in the business there. > We really just have to test them and find out... It will be interesting to > see how much margin is really there. > > IR usually over rates CE voltage by about 100 volts and that is a known > hard limit that we can't go over especially with our currents. Far far > beyond any avalanche current rating! > > > Marco mentions that I am running the gates at pretty high voltage (18V). > IGBTs like these usually "break" at about 50 volts on the gate. No problem > nearing the 20 volt spec there. The 2 9V batteries will quickly go down to > about 16 volts. That is only 6 volts over the full 200 amps on spec and I > am a little worried about noise getting on the gates too so more margin is > nice. Shoot through from the Ccg capacitance is a concern and that is why > I have 100 ohm gate resistors to slow the turn on way down compared to what > it "could" be. > > > Bert mentions "As previously mentioned, a possible downside is that, through > transformer action, some of the secondary's energy will be extracted > during secondary ringdown, resulting in partial recharging of the tank > caps through the internal HexFRED diodes." > > The "theory" is: In order for the primary to take energy back from the > secondary. The primary has to be "tuned". When the IGBT opens, it > destroys the primary as a tuned circuit. Thus the primary will not be able > to take back the energy. We will really just have to see what happens > There. there is a "plan B" of two IGBTs in a CE-EC configuration. But > we'll see if we even have to worry about it. The primary remains coupled to the secondary whether the IGBTs and diodes are conducting or not and will generate some voltage as an open-circuit winding. In my MOSFET expts I had a look at exactly these effects and found that quenching when primary currents were zero was the best time to avoid severe spiking. Interrupting the primary with current flowing was the worst and generated spikes far higher than the supply voltages as the primary was being interrupted at a time when it was generating magnetic flux which was mostly linked to itself. Regards, Malcolm > Cheers, > > Terry > > > > > Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Mon, 19 Aug 2002 17:49:00 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Mon, 19 Aug 2002 17:33:49 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: Re: OLTC Update - Primary circuit resistance. X-Mailing-List: archive/latest/1308 X-Loop: tesla@pupman.com Original poster: "Eddie Burwell by way of Terry Fritz " At 11:46 AM 8/19/02 -0600, you wrote: >Original poster: "Darren Freeman by way of Terry Fritz " > > > >With BJTs and I suppose IGBTs as well, this doesn't work. What happens is >the most conductive part of the die takes a little more current than the >rest, so heating itself up a little hotter. With MOSFETs that would cause >its conductivity to drop and reduce its heating, so the process is >stabilising. But with a BJT the locally heated region becomes more >conductive and the current rises, causing more heating and so on until the >device is destroyed. > >At least it's what I've read, I never pushed insane currents through them >before =) > >Check the Safe Operating Area of the devices and don't expect to push much >past it for too many pulses - there should be a limit to what you can do >even in a once off pulse. Don't count on thermal effects allowing stupidly >high currents =) > > The voltage drop across an IGBT goes up with temperature for large currents. This seems favorable, although the bulk behavior is no guarantee of good behavior on the micro level. The structure of a SCR is similar to that of an IGBT and the ratio of the average current rating to the peak current rating is generally better than BJTs and MOSFETs and IGBTs. As a device manufacturer you don't want your customers driving your products in to latch-up whether they can thermally handel it for a brief time or not. In a full bridge if one device latches on all the magic smoke gets out:( The OLTC could well ride through an over current induced latch-up. Here is a little info on IGBT latch-up http://www.elec.gla.ac.uk/groups/dev_mod/papers/igbt/igbt.html Eddie Burwell Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Wed, 21 Aug 2002 11:53:43 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Wed, 21 Aug 2002 11:45:18 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: RE: OLTC Update - Primary circuit resistance. X-Mailing-List: archive/latest/1325 X-Loop: tesla@pupman.com Original poster: "by way of Terry Fritz " Hi Terry, > -----Original Message----- > From: tesla@pupman.com [mailto:tesla@pupman.com] > Sent: 19. elokuuta 2002 21:22 > To: tesla@pupman.com > Subject: Re: OLTC Update - Primary circuit resistance. > > > Original poster: "Terry Fritz" > > Marco mentions that I am running the gates at pretty high > voltage (18V). > IGBTs like these usually "break" at about 50 volts on the > gate. No problem > nearing the 20 volt spec there. If you are really using the IRG4PF50WD, check carefully its datasheet. Its Vge max value is truly +/- 20V, not 50V. > nice. Shoot through from the Ccg capacitance is a concern > and that is why > I have 100 ohm gate resistors to slow the turn on way down > compared to what > it "could" be. Another thing. You have the 20V TVS on the driver side of the gate resistor, to protect the driver, I suppose. If your IGBT fails, it will go short and you'll get the 500V (or whatever) right onto the gate. So this is a good strategy indeed. But more bucks are lost if you damage the IGBT. To protect the IGBT from transients, I suggest you to put another TVS (or a 16V zener) *directly* from gate to emitter. Otherwise the 100 ohm in series will make its effect null. Best Regards Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Mon, 2 Sep 2002 23:34:06 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Mon, 02 Sep 2002 23:31:04 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: OLTC update - primary IGBT loss X-Mailing-List: archive/latest/1971 X-Loop: tesla@pupman.com Original poster: "Terry Fritz" Hi Bert, Paul, and All, I checked it all out and the 3.8nH inductance and 0.4mOhm resistance of the caps and it is just is not a factor at all. The leads are a concern but there are ten in parallel and all that. However, I think I have "found" some losses ;-)) I dropped two high voltage high bandwidth scope probes directly between the CE leads of a center IGBT (on the leads, right up next to the plastic case) and got this: http://hot-streamer.com/temp/OLTC09-02-03.gif The red line is the CE voltage while the IGBT is on. Seemed a little high so I tried it with both probes going to the same point to check if the 2000 amps was getting on these "cheapo" probes" http://hot-streamer.com/temp/OLTC09-02-04.gif Looks fine! So the IGBT CE waveform is probably very real! I pulled all the waveforms out to a file (99% of you folks don't need to click on this musty old set of 40,000 little numbers ;-)) http://hot-streamer.com/temp/OLTC09-02-05.dta But it all cleans up to the nice CE wave form here: http://hot-streamer.com/temp/OLTC09-02-06.gif We can clearly see where the IGBT kicks it on the high side at about 6 volts and the HEXFRED cuts in at about 5 volts. Note how the HEXFRED easily kills the inductive spikes that are tiny in this case. However, the wave form is not flat-topped as (some IR data sheets would lead us to belive. However, they do give some pessimistic instant current graphs ;-)) Looks like we have a solid diode drop (rather high) and a DC resistance. We'll just call the diode drop 6 volts and the resistance above that as 6/2000 = 0.003 ohms. The current in this case is: http://hot-streamer.com/temp/OLTC09-02-07.gif So at full rated current, this extra resistance is dissipating about 70% more heat in the IGBT as we would normally think from the data sheets. That could "mess up" some designers out there using them :o)))) But we seem to know more and can find where we stand. Funny how Tesla coil's find the "real specs" for this stuff ;-)) Happy to know that the heat is going into the IGBTs where it can be easily handled, If it were going into the caps, that would be a 'bad' thing. So with 6 volts drop and 3mOhms of resistance... At 4500 amps and 560 volts firing... The loss is 4500*6 + 4500^2 * 0.003 = 87750 peak watts (note that 56% of that loss is in this extra IGBT package resistance). The peak system power is 4500 * 560 = 2,520,000 watts. Dividing we get a "Q" of 2,520,000/87750 = 28.7 Paul predicted 30 yesterday (That is why we "listen" to good o'l Paul ;-)))) We can now plug our really good Q number into the equation Rpri = 2 x pi x F x L / Q to find a "nice equivalent resistance" of 3.228 ohms of equivalent primary resistance. Almost all of that is in the IGBTs. Cornell-Dubilier has "played" with use coilers before so they probably double their 0.4mOhm resistance number just for folks like us :-)))) So we need to compare this to a standard primary circuit using high voltage and a spark gap. 28nF, 21000 volts, 85kHz, Req=3 ohms,... Peak current is 314 amps. Peak power loss is 296,000 watts. Peak system power is 314 * 21000 = 6.6Mwatts. Q = 22.3! Oh goody, My primary has a lot higher current and higher Q than a normal Tesla coil!! Q = 28 at 4500 amps!! So it would appear that the basic OLTC machine is sound. It's that darn secondary... Paul predicted a Q of 45 when "we" thought it should be 200... BTW - This peak power loss divided by peak system power seems very useful as does the equation Rpri = 2 x pi x F x L / Q. We can probably carve those into our desk tops ;-))) I see a very large toroid in my future... :-)))) Primary seems fine as long as I can keep whipping off turns... Many thank to Paul for guiding my brain through all this ;-)) Cheers, Terry At 10:10 PM 9/2/2002 -0500, you wrote: >Hi Terry, > >Did you ever make an estimates of capacitor ESR?? Gotta' believe those >flimsy leads also add a fair amount of series resistance in the primary >circuit... > >-- Bert -- >-- >Bert Hickman >Stoneridge Engineering >"Electromagically" (TM) Shrunken Coins! >http://www.teslamania.com > >Tesla list wrote: >> >> Original poster: "Terry Fritz" >> >> Hi Paul, >> >> I was not able to find any time to work on this yeasterday. But today... >> >> The 20,40,60... Volts I gave is a "metered" voltage. The actual firing >> voltage is twice that number. >> >> If Rpri = 2 x pi x F x L / Q >> >> Vfire Qpri Rpri >> >> 40 4.7 0.0197 >> 80 7.3 0.0127 >> 120 10.0 0.00927 >> 160 12.1 0.00766 >> 200 14.0 0.00662 >> >> So the graph looks like: >> >> http://hot-streamer.com/temp/OLTC09-02-01.gif >> >> If one uses your equations below which seem to fit very well: >> >> http://hot-streamer.com/temp/OLTC09-02-02.gif >> >> Looks like I can expect a Q of 21.4 at 4.3mOhms for Rpri. >> >> Vds Seems high here at 8 volts. Probably not too surprising given that so >> many terms are at work in the "real" system. However, if we pump 2000 amps >> peak into the system, the loss for Vds is: >> >> 8*2081 = 16648 watts peak >> >> While the loss for Rpri is: >> >> 2081^2 x 0.00662 = 28668 watts >> >> The system peak power is about 200*2081 = 416kW >> >> Of course, 416000 /(16648 + 28668) = Q = 9.18 here in my guess work. Off >> by the square root of two... >> >> I will have to think about if Rpri or Vds has any reason to be so high. >> Have to think about cap and Lpri second order resonances and other horrific >> things... Probably still have enough drive there in any case, but I just >> like to know exactly "why"... >> >> Cheers, >> >> Terry > > Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Tue, 3 Sep 2002 12:35:43 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Tue, 03 Sep 2002 12:22:44 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: Re: OLTC update - primary IGBT loss X-Mailing-List: archive/latest/1990 X-Loop: tesla@pupman.com Original poster: "Paul Nicholson by way of Terry Fritz " Terry wrote: > Paul predicted a Q of 45 when "we" thought it should be 200... Ah, the '45' isn't a prediction - its a measured value extracted by tcma from your secondary ringdown. My best Q prediction is 79, which is obtained by considering the wire AC resistance but not the proximity loss or other losses due to coupling with the surroundings. Usually these Q predictions are a factor 2 to 4 higher than obtained in practice because of all the extra un-accounted losses that affect the real coil. The actual figure of 45 seems pretty reasonable under the circumstances. I agree with your revised figures for the primary. The OLTC faces two challenges, one being the low impedance of the primary (copper losses and Vds become significant) and the other being the low frequency of the secondary (large Lsec leads to high copper and proximity loss). Neither of these difficulties is at all surprising, since you're asking for an overall voltage transformation which is a factor 100 times what a normal TC achieves. That's a tough proposition and it's great that it's working so well. The question now is whether these low Q factors lead to low power-to- streamer efficiency, which in turn depends on how quickly the streamers form. Do they take a quarter-cycle, or maybe a few cycles, or does it require repeated bangs? Those questions lead us to where the tssp project is right now. We need to get that topvolts probe sorted out. Can you use a fibre-optic current probe between topload and breakout point? That would give us the streamer current. We could at least see where in the RF cycle the streamers are taking current. I'm having trouble modeling your triple parallel turn primary - the interaction between the three is not modeled by the tssp software and they are too far apart to model as a single turn. This is why I haven't sent any V/I profiles. -- Paul Nicholson -- Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Tue, 3 Sep 2002 12:36:55 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Tue, 03 Sep 2002 12:23:09 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: RE: OLTC update - primary IGBT loss X-Mailing-List: archive/latest/1992 X-Loop: tesla@pupman.com Original poster: "Lau, Gary by way of Terry Fritz " Hi Terry: While primary circuit Q has always been viewed as important, I recall many considered opinions suggesting that secondary Q was not so critical. Suggestions were made to wind secondaries with Litz wire, and the prevailing response was that secondary losses (in disruptive coils) were not worth fretting over. Please help me to reconcile this with your secondary situation. Is your secondary just outrageously more lossy than a typical secondary coil? Thanks, Gary Lau MA, USA Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Tue, 3 Sep 2002 12:43:40 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Tue, 03 Sep 2002 12:40:42 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: Re: OLTC update - primary IGBT loss X-Mailing-List: archive/latest/1999 X-Loop: tesla@pupman.com Original poster: "Greg Leyh by way of Terry Fritz " --- >Original poster: "Terry Fritz" > >Hi Bert, Paul, and All, > >I checked it all out and the 3.8nH inductance and 0.4mOhm resistance of the >caps and it is just is not a factor at all. The leads are a concern but >there are ten in parallel and all that. However, I think I have "found" >some losses ;-)) > >I dropped two high voltage high bandwidth scope probes directly between the >CE leads of a center IGBT (on the leads, right up next to the plastic case) >and got this: > > http://hot-streamer.com/temp/OLTC09-02-03.gif > >The red line is the CE voltage while the IGBT is on. Hi Terry, That's an impressive bit of current to push through a PCB mountable package! Do you have 3 IGBTs in parallel here, as per the earlier sketch? How well do they share the current? At 33kHz and 4500A pk that's a max dI/dt of about 940 A/uS. 10nH will drop 9.4V at that speed, so a noticeable percentage your measured drops might be reactive, instead of purely resistive. It appears that the emitter voltage on the first scope trace starts out the pulse at 115 volts below ground? Or is this just a scope offset? I was also wondering if the forward IGBT voltage drop and the reverse current drop due to the back diode are about the same? It's difficult to tell where zero is, on the math trace. -GL --- Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Tue, 3 Sep 2002 13:02:03 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Tue, 03 Sep 2002 13:00:16 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: RE: OLTC update - primary IGBT loss X-Mailing-List: archive/latest/2002 X-Loop: tesla@pupman.com Original poster: "Terry Fritz" Hi Greg, At 11:08 AM 9/3/2002 -0700, you wrote: >--- > > >>Original poster: "Terry Fritz" >> >>Hi Bert, Paul, and All, >> >>I checked it all out and the 3.8nH inductance and 0.4mOhm resistance of the >>caps and it is just is not a factor at all. The leads are a concern but >>there are ten in parallel and all that. However, I think I have "found" >>some losses ;-)) >> >>I dropped two high voltage high bandwidth scope probes directly between the >>CE leads of a center IGBT (on the leads, right up next to the plastic case) >>and got this: >> >> http://hot-streamer.com/temp/OLTC09-02-03.gif >> >>The red line is the CE voltage while the IGBT is on. > > >Hi Terry, > >That's an impressive bit of current to push through a PCB >mountable package! Do you have 3 IGBTs in parallel here, >as per the earlier sketch? How well do they share the >current? There are 10 IGBTs in the system. I have tested them to 700 amps "each"!! So the whole thing could probably do 7000 amps. But they really only need to do about 4500 amps when I go to 240VAC. Here is the primary IGBT array: http://hot-streamer.com/temp/OLTC08-31-03.jpg http://hot-streamer.com/temp/OLTC08-31-04.jpg Here is the single IGBT test: http://hot-streamer.com/temp/OLTC08-30-01.jpg http://hot-streamer.com/temp/OLTC08-30-02.gif > >At 33kHz and 4500A pk that's a max dI/dt of about 940 A/uS. >10nH will drop 9.4V at that speed, so a noticeable percentage >your measured drops might be reactive, instead of purely >resistive. I do note that the Vce is about 90 degrees out of phase with the primary voltage. The internal inductance of the emitter is speced at 13nH. 36500Hz and 450 amps gives a reactive voltage drop of... 1.34 volts. If one can beleive the spec, I should hardly see that in the test I did (about 0.6 volts). > >It appears that the emitter voltage on the first scope trace >starts out the pulse at 115 volts below ground? Or is this >just a scope offset? I was trying to differentially measure 10 volts out of 200VAC at 36500Hz ;-)) I was turning level knobs and all like crazy. Ignore any offsets. > >I was also wondering if the forward IGBT voltage drop and the >reverse current drop due to the back diode are about the same? >It's difficult to tell where zero is, on the math trace. You can see it here: http://hot-streamer.com/temp/OLTC09-02-06.gif The top glitches at about 6 volts is the IGBT Vdrop and the lower glitch at about -5 volts (the scale in the chart is X10). The current is about 200 amps per IGBT. The reverse diode seems to work wonderfuly! Cheers, Terry > >-GL > > >--- > Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Tue, 3 Sep 2002 13:18:23 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Tue, 03 Sep 2002 13:16:27 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: RE: OLTC update - primary IGBT loss X-Mailing-List: archive/latest/2003 X-Loop: tesla@pupman.com Original poster: "Terry Fritz" Hi Gary, There are two factors at work here. First, I am trying to make the thing really efficient so I am fretting about power losses. I suppose I could just dump a whole lot more power into it but then the over all efficiency might be "only" as good as a typical coil. ;-) Second, the voltage gain is really high SQRT (0.492/404e-9) = 1103!! The gain of my big coil is only SQRT(0.075/132e-6) = 24. Max voltage for each is: 1103 * 560 = 617680 24 * 21000 = 504000 That seems about right from that point of view... It may be that I was trying way to hard for voltage gain and I over did it at the expense of current to drive the streamer. I may have way too high of output impedance. I am studying all this now so I don't have the answer yet. However, I suspect going to a much larger toroid and pulling turns off the secondary (low voltage and higher current) would be a good thing (but taking wire off is a whole lot easier than trying to put it back on ;-)). The Q's are sort of low, but they alone should not be a critical problem. If the output impedance is way off, that is a big problem that only amplifies the Q losses. We don't normally worry much about this stuff because it is messy and we just hope it's ok. I seem to have found a case where it is all very important! Much to ponder... Cheers, Terry At 11:48 AM 9/3/2002 -0400, you wrote: >Hi Terry: > >While primary circuit Q has always been viewed as important, I recall many >considered opinions suggesting that secondary Q was not so critical. >Suggestions were made to wind secondaries with Litz wire, and the prevailing >response was that secondary losses (in disruptive coils) were not worth >fretting over. Please help me to reconcile this with your secondary >situation. Is your secondary just outrageously more lossy than a typical >secondary coil? > >Thanks, Gary Lau >MA, USA > > Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Tue, 3 Sep 2002 13:41:44 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Tue, 03 Sep 2002 13:40:02 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: Re: OLTC update - primary IGBT loss X-Mailing-List: archive/latest/2004 X-Loop: tesla@pupman.com Original poster: "Terry Fritz" Hi Paul, At 03:18 PM 9/3/2002 +0100, you wrote: > >The question now is whether these low Q factors lead to low power-to- >streamer efficiency, which in turn depends on how quickly the streamers >form. Do they take a quarter-cycle, or maybe a few cycles, or does >it require repeated bangs? That certainly appears to be a big factor here! I may have lots of instant voltage but not enough energy to sustain the power to feed a big streamer. > >Those questions lead us to where the tssp project is right now. We need >to get that topvolts probe sorted out. You know, electronic OLTC coils can operate at very low levels with high accuracy and repeatability (no spark gap to jump). Perhaps instead of getting a probe to measure 500,000 volts, we need a coil that can go down to 60,000 volts... :-))) One could then do real time streamer voltage and current (might be a sort of small streamer). One would have to time shift the current signal to allow for propagation delay in the glass fiber optics (~30nS). Also the voltage probe would have a little capacitance loading. Would be interesting. If I had three channels I could do base current at the same time. One very nice thing about the OLTC is that there are no high voltage drive circuits, everything in the primary side can easily be directly probed. > >Can you use a fibre-optic current probe between topload and breakout >point? That would give us the streamer current. We could at least >see where in the RF cycle the streamers are taking current. Sure! Tonight I'll work on such things. > >I'm having trouble modeling your triple parallel turn primary - the >interaction between the three is not modeled by the tssp software and >they are too far apart to model as a single turn. This is why I >haven't sent any V/I profiles. The three turn primary was nice in that it gave lower Lpri. But from a theoretical and modeling point of view, it sure is a pain. I wonder if coupling in three spread out rings hurts the waveform on the secondary. A point source would be best. Three rings may be like trying to set up a standing wave on a rope with three people holding onto it shaking in unison but in different places. Maybe it could be modeled by superposition where you do each one and then just add the numbers. Not sure... A messy problem. You don't need to worry with it unless you really want to. Cheers, Terry >-- >Paul Nicholson >-- > Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Tue, 3 Sep 2002 18:49:51 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Tue, 03 Sep 2002 18:28:49 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: RE: OLTC update - primary IGBT loss X-Mailing-List: archive/latest/2013 X-Loop: tesla@pupman.com Original poster: "John H. Couture by way of Terry Fritz " Terry, All - The gif figure shown below of a real world dampened curve can be used to find the Q Factor using the 10% method indicated in my Tesla Coil Notebook. It is only an approximation so I doubt you will find this in any other publication. The curve has the typical exponential form of the dampened wave. All you have to do is measure the the curve on your computer screen and find the number of cycles it takes to reach the 10% amplitude. It is only an approximation but your calculated Q can then be compared with the real world test curve. Q = 3.1416/log dec and Q = 3.1416/ln(10) times the number of cycles to 10% amplitude. The curve appears to be roughly about 14 cycles to 10%. This would give a Q Factor of about Q = 3.1416/ln(10) * 14 = 19.10 This Q is pretty close to the 22 to 28 you are finding. Could the difference be due to the resistance you selected and it should be slightly changed? It looks like it is close to Paul's 79/4 factor = 19.75 Q Factor Also, the approximate percent reduction per cycle can be found as follows: Log dec = 3.1416/Q = 3.1416/19.01 = .1653 a1/a3 = e^.1653 = 1.1797 Percent reduction = 100/1.1797 = 84.77% John Couture -------------------------- -----Original Message----- From: Tesla list [mailto:tesla@pupman.com] Sent: Monday, September 02, 2002 10:31 PM To: tesla@pupman.com Subject: OLTC update - primary IGBT loss Original poster: "Terry Fritz" Hi Bert, Paul, and All, ---------------------------- snip Current in this case is: http://hot-streamer.com/temp/OLTC09-02-07.gif So at full rated current, this extra resistance is dissipating about 70% more heat in the IGBT as we would normally think from the data sheets. That could "mess up" some designers out there using them :o)))) But we seem to know more and can find where we stand. Funny how Tesla coil's find the "real specs" for this stuff ;-)) Happy to know that the heat is going into the IGBTs where it can be easily handled, If it were going into the caps, that would be a 'bad' thing. So with 6 volts drop and 3mOhms of resistance... At 4500 amps and 560 volts firing... The loss is 4500*6 + 4500^2 * 0.003 = 87750 peak watts (note that 56% of that loss is in this extra IGBT package resistance). The peak system power is 4500 * 560 = 2,520,000 watts. Dividing we get a "Q" of 2,520,000/87750 = 28.7 Paul predicted 30 yesterday (That is why we "listen" to good o'l Paul ;-)))) We can now plug our really good Q number into the equation Rpri = 2 x pi x F x L / Q to find a "nice equivalent resistance" of 3.228 ohms of equivalent primary resistance. Almost all of that is in the IGBTs. Cornell-Dubilier has "played" with use coilers before so they probably double their 0.4mOhm resistance number just for folks like us :-)))) So we need to compare this to a standard primary circuit using high voltage and a spark gap. 28nF, 21000 volts, 85kHz, Req=3 ohms,... Peak current is 314 amps. Peak power loss is 296,000 watts. Peak system power is 314 * 21000 = 6.6Mwatts. Q = 22.3! Oh goody, My primary has a lot higher current and higher Q than a normal Tesla coil!! Q = 28 at 4500 amps!! So it would appear that the basic OLTC machine is sound. It's that darn secondary... Paul predicted a Q of 45 when "we" thought it should be 200... BTW - This peak power loss divided by peak system power seems very useful as does the equation Rpri = 2 x pi x F x L / Q. We can probably carve those into our desk tops ;-))) I see a very large toroid in my future... :-)))) Primary seems fine as long as I can keep whipping off turns... Many thank to Paul for guiding my brain through all this ;-)) Cheers, Terry Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Tue, 3 Sep 2002 18:48:58 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Tue, 03 Sep 2002 18:29:51 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: RE: OLTC update - primary IGBT loss X-Mailing-List: archive/latest/2017 X-Loop: tesla@pupman.com Original poster: "Malcolm Watts by way of Terry Fritz " Hi Gary, I'd like to make some comments although this is addressed to Terry: On 3 Sep 2002, at 12:23, Tesla list wrote: > Original poster: "Lau, Gary by way of Terry Fritz " > > Hi Terry: > > While primary circuit Q has always been viewed as important, I recall many > considered opinions suggesting that secondary Q was not so critical. I think that if I have been guilty of making such statements in the past, it was based on the assumption that the de-facto standard guidelines for building the coil were being met (e.g. a thousand turns or so, h/d 3 - 5, and so on. In the past, I have deliberately wound bad secondaries to gauge their effect and always, without exception, found them to suffer difficulties ranging from very high losses to serious over-volting with moderate amounts of Ep. Sometimes, one can get the most bizarre effects from them by driving them way off tune (e.g. corona looping from the top to 1/3 way down the winding) but for serious coiling, they were never going to hack it. Secondary Q *is* important - prior to breaking out at each bang, you want the output voltage to go as high as possible and in the case of a heavily toploaded coil, it can mean the difference between being able to breakout and a bad case of racing arcs. > Suggestions were made to wind secondaries with Litz wire, and the > prevailing response was that secondary losses (in disruptive coils) were > not worth fretting over. Please help me to reconcile this with your > secondary situation. Is your secondary just outrageously more lossy than a > typical secondary coil? IMO, yes. I've seen bad performance from low-L coils and very high-L coils. There is definitely a happy medium to be found for a given physical coil size. Regards, malcolm Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Tue, 3 Sep 2002 18:38:38 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Tue, 03 Sep 2002 18:30:21 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: RE: OLTC update - primary IGBT loss X-Mailing-List: archive/latest/2015 X-Loop: tesla@pupman.com Original poster: "Malcolm Watts by way of Terry Fritz " Hi Terry, On 3 Sep 2002, at 13:16, Tesla list wrote: > Original poster: "Terry Fritz" > > Hi Gary, > > There are two factors at work here. > > First, I am trying to make the thing really efficient so I am fretting > about power losses. I suppose I could just dump a whole lot more power > into it but then the over all efficiency might be "only" as good as a > typical coil. ;-) > > Second, the voltage gain is really high SQRT (0.492/404e-9) = 1103!! The > gain of my big coil is only SQRT(0.075/132e-6) = 24. Max voltage for each is: > > 1103 * 560 = 617680 > 24 * 21000 = 504000 > > That seems about right from that point of view... I don't think the equivalent shunt impedance will allow the voltage gain to be anything like 1103. The coil Q is a direct reflection of the coil's ESR and by a simple equivalence transform, its output/shunt impedance. I'd say that your proposed method for correcting the problem is probably only going to work if you rewind with bigger wire and a much bigger topload with a rather modest ROC. Regards, Malcolm > It may be that I was trying way to hard for voltage gain and I over did it > at the expense of current to drive the streamer. I may have way too high > of output impedance. I am studying all this now so I don't have the answer > yet. However, I suspect going to a much larger toroid and pulling turns > off the secondary (low voltage and higher current) would be a good thing > (but taking wire off is a whole lot easier than trying to put it back on > ;-)). The Q's are sort of low, but they alone should not be a critical > problem. If the output impedance is way off, that is a big problem that > only amplifies the Q losses. We don't normally worry much about this stuff > because it is messy and we just hope it's ok. I seem to have found a case > where it is all very important! > > Much to ponder... > > Cheers, > > Terry > > > At 11:48 AM 9/3/2002 -0400, you wrote: > >Hi Terry: > > > >While primary circuit Q has always been viewed as important, I recall many > >considered opinions suggesting that secondary Q was not so critical. > >Suggestions were made to wind secondaries with Litz wire, and the prevailing > >response was that secondary losses (in disruptive coils) were not worth > >fretting over. Please help me to reconcile this with your secondary > >situation. Is your secondary just outrageously more lossy than a typical > >secondary coil? > > > >Thanks, Gary Lau > >MA, USA > > > > > > > Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Tue, 3 Sep 2002 18:39:40 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Tue, 03 Sep 2002 18:35:21 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: Re: OLTC update - primary IGBT loss X-Mailing-List: archive/latest/2019 X-Loop: tesla@pupman.com Original poster: "Paul Nicholson by way of Terry Fritz " Terry wrote: > I do note that the Vce is about 90 degrees out of phase with the > primary voltage. That's to be expected, since Vce (resistive) is in phase with Ip and therefore 90 degrees from Vp. > The internal inductance of the emitter is speced at 13nH. which translates to 2*pi*F*L = 0.003 ohms reactive. In conjunction with your estimated 0.003 resistance, we'd expect a phase angle between Ip and Vce of arctan( 2*pi*F*L/R) = 45 degrees. When I look at your http://hot-streamer.com/temp/OLTC09-02-03.gif I see the Vce at about 88.5 deg from Vp. I don't see much sign of the claimed 13nH. An Ip trace would help to settle the matter. Come to think of it, if you had 13nH in the emitter, wouldn't that be upsetting the drive signal Vbe by a few volts? Something's not quite adding up here. > The three turn primary was nice in that it gave lower Lpri. But > from a theoretical and modeling point of view, it sure is a pain. Yes. What I'll do is 'fabricate' a cylindrical primary that gives the same k factor and tuning. It'll have the same radius and overall height and will be approximately 1 turn. Then we can get some sort of a model, and we can try to predict the effect of hacking the secondary down to a lower L/C ratio. You'll trade volts for charge and it will be interesting to see the effect. Probably end up with a wide but thin toroid - bicycle tyre shape :). Hope we can get a lot of data from the big L sec before you start to unwind. > A messy problem. You don't need to worry with it unless you really > want to. It would be quite a job to add that in. I've been contemplating adding in the stuff to model the capacitively coupled dual resonator, which is less daunting than this. We're some way off being able to model arbitrary resonators by just bolting together the integral operators for each distributed reactive component, but that's where it's heading if you guys insist on doing these ruddy non-standard coils! In fact, putting together the integral operators is the easy bit. You end up with a big matrix of complex numbers that describes the whole resonator, and the hard bit is to find the vectors (voltage and current profiles) which pass through this matrix unchanged. These are the resonant modes of the system. There's no way to solve this computing problem in a general way for an arbitrary resonator matrix and you have to apply heuristics with some fore knowledge of the pattern of solutions for the particular resonator layout involved. > I wonder if coupling in three spread out rings hurts the waveform > on the secondary. No sign of a problem. The FT of your beat envelope shows only the normal amount of higher mode ringing. No sign of HF modes from the primary either, so no racing arcs from this cause! >> Can you use a fibre-optic current probe between topload and breakout >> point? That would give us the streamer current. We could at least >> see where in the RF cycle the streamers are taking current. > Sure! Tonight I'll work on such things. That would tell us a great deal, qualitatively, I think. > Perhaps instead of getting a probe to measure 500,000 volts, we need > a coil that can go down to 60,000 volts... :-))) The solid state coils certainly are appealing - controllable, nice clean waveforms. Operating at lower voltages with a smaller coil does have some appeal. Probing the coil has a greater relative effect so proportionally more care is needed to account for these effects. Also, it is not clear how conclusions drawn from a few cm of streamer are to be scaled up to normal sized coils. I'm sure we could tackle these problems, and it would be better to make some progress by looking at a low voltage breakout, than not do anything at all. -- Paul Nicholson -- Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Wed, 4 Sep 2002 08:32:11 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Wed, 04 Sep 2002 08:25:28 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: Re: OLTC update - primary IGBT loss X-Mailing-List: archive/latest/2045 X-Loop: tesla@pupman.com Original poster: "Paul Nicholson by way of Terry Fritz " Terry wrote: > I wonder if coupling in three spread out rings hurts the waveform > on the secondary. I wrote: > No sign of a problem. The FT of your beat envelope shows only the > normal amount of higher mode ringing. No sign of HF modes from > the primary either, so no racing arcs from this cause! On a closer look, there is quite a large initial excitation of higher modes, but these are decaying quite rapidly due to low Q. So overall the energy is quite low on the FT, but it's concentrated in the first cycle or two of the bang. The resulting initial high dI/dt near the coil base might eventually give an excessive vertical gradient across the lower turns. Terry wrote: > I hooked up the 60kV Jennings probe to the OLTC tonight: > http://hot-streamer.com/temp/OLTC09-03-02.jpg > http://hot-streamer.com/temp/OLTC09-03-01.gif > http://hot-streamer.com/temp/OLTC9-3v.CSV > http://hot-streamer.com/temp/OLTC9-3i.CSV Ok, I got the model lined up. I've setup a single turn dummy primary to have the same k and Lp as your system exhibits. I've had to do three 'fiddles': An extra 7pF to the topload to allow for the Jennings, and some extra Rp and Rs to line up the model's Q factors with results of tcma analysis of your ringdowns. The rest of the model comes entirely from your geometry. The resulting time domain response of the model compared with your waveforms is in http://www.abelian.demon.co.uk/tssp/tmp/OLTC09-03a.gif The match of the higher mode components is quite poor, Q, F and phase errors are showing up here - thus the fine detail of the waveform is not properly modeled. This may be due to the coating you have over the secondary which will modify the internal C in an unmodeled way, and may also be due to my 'virtual primary'. Still, it's not a problem for this exercise so I won't investigate further. The primary Q is very low at these small voltages. That's going to be an embuggerance later on - if Q depends strongly on Vpri then it will be tricky to compare below/above breakout waveforms. To get around this we'd have to characterise the primary Q/Vpri function, as we've already done, but more accurately. Then we can make proper allowance for the intrinsic primary Q as the voltage goes above breakout. Incidentally, the sec Q is up a little from 45 to 53, and the tuning seems a little funny because the Fsec has dropped due to the probe but Fpri remains the same. Returning to the issue of higher mode excitation, note your initial -ve going Ibase transient peaks at roughly half the peak Ibase. Compare that with say Marco's Thor system. http://www.abelian.demon.co.uk/tssp/md110701/ or some of your earlier solid state gap tests, http://www.abelian.demon.co.uk/tssp/tfss270501/ In these and other similar cases, the initial transient Ibase is only around 1/10th or less of the peak Ibase. So I'd say the higher modes are quite high, but just look weak on the FT because they decay quickly. Note that this higher mode excitation is not a result of your switching, but is intrinsic to the geometry of the resonator - your OLTC dual resonator has a rich and bright tone with a quick decay - a bit of a tin can sound if you could hear it. The animation is in http://www.abelian.demon.co.uk/tssp/tmp/OLTC09-03a.anim.gif and you can clearly see the initial transient ripple. It doesn't seem to excite much voltage along the secondary, but that's a little misleading, because it is the dV/dx that causes the breakdown. The voltage gradient animation is http://www.abelian.demon.co.uk/tssp/tmp/OLTC09-03a.grad.gif which shows the radial and vertical E-field strengths along the surface of the secondary. Now you can see where the potential (excuse pun) for breakdown comes. If your secondary is going to break down at some power level, it will be in the bottom 10% of turns, I'd say. All in all, I'd say the OLTC looks reasonably manageable for some breakout tests. > I am wondering if this is useful to you Oh yes, > and what you would like to see? Breakout! But from a well defined surface, eg a small sphere or toroid. I have to model its surface field so it must be on the axis of the coil. I guess it will take some experiment to find a low voltage breakout from a suitable small ROC object, bearing in mind the Jennings ratings. I'll bet you could push those ratings a bit though :) Question is, can you obtain a suitable breakout in a single-shot mode? Because I'd like to look at the waveforms for a single shot, then for the second shot of a pair, then the 3rd shot of a triplet, etc. -- Paul Nicholson -- Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Wed, 4 Sep 2002 13:09:32 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Wed, 04 Sep 2002 13:07:30 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: Re: OLTC update - primary IGBT loss X-Mailing-List: archive/latest/2056 X-Loop: tesla@pupman.com Original poster: "Terry Fritz" Hi Paul, At 01:58 PM 9/4/2002 +0100, you wrote: >Terry wrote: >> I wonder if coupling in three spread out rings hurts the waveform >> on the secondary. > >I wrote: >> No sign of a problem. The FT of your beat envelope shows only the >> normal amount of higher mode ringing. No sign of HF modes from >> the primary either, so no racing arcs from this cause! Ok. That's great news :-) > >On a closer look, there is quite a large initial excitation of higher >modes, but these are decaying quite rapidly due to low Q. So overall >the energy is quite low on the FT, but it's concentrated in the first >cycle or two of the bang. The resulting initial high dI/dt near the >coil base might eventually give an excessive vertical gradient across >the lower turns. > This coil likes to arc to the primary at about 8% up the secondary coil. There is a copper edge there too that does not help. A bundle of poly sheet fixes this. >Terry wrote: >> I hooked up the 60kV Jennings probe to the OLTC tonight: >> http://hot-streamer.com/temp/OLTC09-03-02.jpg >> http://hot-streamer.com/temp/OLTC09-03-01.gif >> http://hot-streamer.com/temp/OLTC9-3v.CSV >> http://hot-streamer.com/temp/OLTC9-3i.CSV > >Ok, I got the model lined up. I've setup a single turn dummy primary >to have the same k and Lp as your system exhibits. I've had to do >three 'fiddles': An extra 7pF to the topload to allow for the Jennings, It is 3pF plus the wire and the added geometry. The total of 7pF sounds right. It lowered Fo from 38.3 to about 35.3. >and some extra Rp and Rs to line up the model's Q factors with results >of tcma analysis of your ringdowns. The rest of the model comes >entirely from your geometry. > >The resulting time domain response of the model compared with your >waveforms is in > > http://www.abelian.demon.co.uk/tssp/tmp/OLTC09-03a.gif Nice! Shows the mechanics are all basically working. > >The match of the higher mode components is quite poor, Q, F and phase >errors are showing up here - thus the fine detail of the waveform is >not properly modeled. This may be due to the coating you have over >the secondary which will modify the internal C in an unmodeled way, I need to try wrapping another coil to see if that affects anything like Antonio suggested. >and may also be due to my 'virtual primary'. Still, it's not a >problem for this exercise so I won't investigate further. > >The primary Q is very low at these small voltages. That's going to be >an embuggerance later on - if Q depends strongly on Vpri then it will >be tricky to compare below/above breakout waveforms. To get around >this we'd have to characterise the primary Q/Vpri function, as we've >already done, but more accurately. Then we can make proper allowance >for the intrinsic primary Q as the voltage goes above breakout. > The Vpri voltage could be held constant and we could control breakout with the terminal. A pin point will breakout very easily were the toroid does not at a given voltage. >Incidentally, the sec Q is up a little from 45 to 53, Really!! I wonder if it is due to the added C of the probe. The probe's added C is very high Q. >and the tuning >seems a little funny because the Fsec has dropped due to the probe >but Fpri remains the same. I did not retune the coil for the added probe C since I didn't want to fiddle too much. > >Returning to the issue of higher mode excitation, note your initial >-ve going Ibase transient peaks at roughly half the peak Ibase. >Compare that with say Marco's Thor system. I think I have much higher coupling! ~0.25 > > http://www.abelian.demon.co.uk/tssp/md110701/ > >or some of your earlier solid state gap tests, > > http://www.abelian.demon.co.uk/tssp/tfss270501/ > >In these and other similar cases, the initial transient Ibase is >only around 1/10th or less of the peak Ibase. > >So I'd say the higher modes are quite high, but just look weak on the >FT because they decay quickly. > >Note that this higher mode excitation is not a result of your >switching, but is intrinsic to the geometry of the resonator - your >OLTC dual resonator has a rich and bright tone with a quick decay - a >bit of a tin can sound if you could hear it. > >The animation is in > > http://www.abelian.demon.co.uk/tssp/tmp/OLTC09-03a.anim.gif > >and you can clearly see the initial transient ripple. It doesn't seem >to excite much voltage along the secondary, but that's a little >misleading, because it is the dV/dx that causes the breakdown. >The voltage gradient animation is > > http://www.abelian.demon.co.uk/tssp/tmp/OLTC09-03a.grad.gif > >which shows the radial and vertical E-field strengths along the >surface of the secondary. Now you can see where the potential (excuse >pun) for breakdown comes. If your secondary is going to break down at >some power level, it will be in the bottom 10% of turns, I'd say. > >All in all, I'd say the OLTC looks reasonably manageable for some >breakout tests. > >> I am wondering if this is useful to you > >Oh yes, > >> and what you would like to see? > >Breakout! But from a well defined surface, eg a small sphere or >toroid. Is a pin point OK? Breaks out at very low voltage and easy to remove for no breakout with little other effect. >I have to model its surface field so it must be on the >axis of the coil. I guess it will take some experiment to find a >low voltage breakout from a suitable small ROC object, bearing in mind >the Jennings ratings. I'll bet you could push those ratings a bit >though :) If the probe breaks down, there are many layers of protection between it and the scope. But I fear the probe would be damaged if the coil hit it hard. They are "rare" if not antiques... > >Question is, can you obtain a suitable breakout in a single-shot mode? >Because I'd like to look at the waveforms for a single shot, then for >the second shot of a pair, then the 3rd shot of a triplet, etc. The primary can simply be charged with a DC power supply through a resistor (isn't that neat!! ;-)) The arbitrary signal generator can be hooked right to the controller to pulse the coil in just about any way imaginable. Since the primary and all is running at conventional voltages. It is extremely easy to control things. I bet firing frequency is really interesting ;-)) I can also quench just about anywhere too. In fact - I can charge, fire, quench, recharge, and refire long before the secondary rings down... No other coil on earth can do that (maybe Ken's can?)! Sort of like the firing difference between a flint lock and a machine gun! Almost a CW-disruptive coil... Even though this coil operates in conventional modes, it is all electronically controlled. Without the high voltage primary and conventional spark gap to worry about and with the all conventual electronic controls, controlling the coil to one's whim is trivial. Wonder what happens if one refires 180 degree off from the present ring... That should send some shock waves up the secondary ! :o)) Cheers, Terry >-- >Paul Nicholson >-- > Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Wed, 4 Sep 2002 16:54:41 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Wed, 04 Sep 2002 16:47:11 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: Re: OLTC update - primary IGBT loss X-Mailing-List: archive/latest/2060 X-Loop: tesla@pupman.com Original poster: "Paul Nicholson by way of Terry Fritz " Terry wrote: > Wonder what happens if one refires 180 degree off from the present > ring... That should send some shock waves up the secondary ! :o)) Oh, what madness is this! I modeled the situation where: just as the primary energy is momentarily zero at the peak of the first beat, we re-stock the primary cap with another bangs worth of energy (eg by switching to a second cap bank - one that you charged up while the 1st bank was going through its first half-beat). The normal ringdown, without quenching, is http://www.abelian.demon.co.uk/tssp/tmp/tfoltc-c1.gif and the double-bang event is in http://www.abelian.demon.co.uk/tssp/tmp/tfoltc-c2.gif The second cap is switched in at 50uS. Following this, instead of the secondary energy ringing down, it does another cycle or so at a slightly higher Vtop. Note that the Ipri and Vpri don't exceed their original values, so no extra device stress. The follow up bang roughly doubles the number of cycles that the secondary could be extending streamers over. No doubt some fun could be had modeling various timings, but you can explore that better with a lumped circuit sim than I can with a distributed model. > I need to try wrapping another coil to see if that affects > anything like Antonio suggested. Well if you do, ping the coil before and after so we can see how much it changes. > I did not retune the coil for the added probe C since I didn't > want to fiddle too much Yeah, that's fine. I don't care what the tuning is, so long as it stays put. It's a major ball ache to recompute everything if something is shifted. > I think I have much higher coupling! ~0.25 Indeed. > This coil likes to arc to the primary at about 8% up the secondary > coil. That would coincide with the location of highest radial field strength shown in the gradient animation. > Is a pin point OK? Depends what we want to know. My particular interest is in witnessing the expected 26kV/cm surface gradient in action, and to observe the extent of the topvolts clamping action. For that we need a predictable breakout surface, so a point is out. I can manage with a small ball, or a rod with a smooth hemispherical tip. The rod or ball must be vertically above the axis of the coil/toroid so that the whole system has cylindrical symmetry. Single shot only for now. But then if we simply want to know whether streamers evolve over part of a cycle, a couple of cycles, or several consecutive bangs, then any old breakout point would do I suppose. Don't need a topvolts measurement for that, just the current to the breakout point, along with Ibase. We might find that we can go a long way just on that basis, eg we can integrate the breakout current to see how much charge is upheld. We can tabulate upheld charge with observed streamer length. We can also look for signs of streamer evolution preferentially on one polarity. Either way, tons of stuff to go at. -- Paul Nicholson -- Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Thu, 5 Sep 2002 22:27:14 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Thu, 05 Sep 2002 22:22:30 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: Re: OLTC update - primary IGBT loss X-Mailing-List: archive/latest/2156 X-Loop: tesla@pupman.com Original poster: "Terry Fritz" Hi Paul, At 09:05 PM 9/4/2002 +0100, you wrote: >Terry wrote: >> Wonder what happens if one refires 180 degree off from the present >> ring... That should send some shock waves up the secondary ! :o)) > >Oh, what madness is this! > >I modeled the situation where: just as the primary energy is >momentarily zero at the peak of the first beat, we re-stock the >primary cap with another bangs worth of energy (eg by switching >to a second cap bank - one that you charged up while the 1st bank >was going through its first half-beat). > >The normal ringdown, without quenching, is > > http://www.abelian.demon.co.uk/tssp/tmp/tfoltc-c1.gif > >and the double-bang event is in > > http://www.abelian.demon.co.uk/tssp/tmp/tfoltc-c2.gif > >The second cap is switched in at 50uS. Following this, instead >of the secondary energy ringing down, it does another cycle or so at a >slightly higher Vtop. Note that the Ipri and Vpri don't exceed >their original values, so no extra device stress. The follow up bang >roughly doubles the number of cycles that the secondary could be >extending streamers over. It appears that the SonoTube will not be transmuted into gold bullion from this exercise ;-)) However, the possibility to change very pure silicon into a molten blob of SiO2 is high. We'll just forget that one ;-))) > >> I need to try wrapping another coil to see if that affects >> anything like Antonio suggested. > >Well if you do, ping the coil before and after so we can see how much >it changes. Darn..., got too late tonight to do this :-( > >> I did not retune the coil for the added probe C since I didn't >> want to fiddle too much > >Yeah, that's fine. I don't care what the tuning is, so long as it >stays put. It's a major ball ache to recompute everything if something >is shifted. Yeah, Don't wan't to go changing too many things at one time. Models don't care if it is out of tune... They still work anyway... > >> Is a pin point OK? > >Depends what we want to know. My particular interest is in witnessing >the expected 26kV/cm surface gradient in action, and to observe the >extent of the topvolts clamping action. For that we need a predictable >breakout surface, so a point is out. I can manage with a small ball, >or a rod with a smooth hemispherical tip. The rod or ball must be >vertically above the axis of the coil/toroid so that the whole system >has cylindrical symmetry. Single shot only for now. I could not find any really good stuff for this. So I ordered up some threaded brass balls from MSC. 1, 1+3/8, and 1+7/8 inch diameter. 1/4 and 3/8 inch thread to match my stuff. Next week... My other post tonight shows that I can see breakout and streamer formation to a very high accuracy. > >But then if we simply want to know whether streamers evolve over >part of a cycle, a couple of cycles, or several consecutive bangs, >then any old breakout point would do I suppose. But real ROCs are best. Best to eliminate as many variables as possible there!!! >Don't need a topvolts >measurement for that, just the current to the breakout point, along >with Ibase. That is toooooo easy!!!!!! ;-))) >We might find that we can go a long way just on that >basis, eg we can integrate the breakout current to see how much charge >is upheld. We can tabulate upheld charge with observed streamer length. >We can also look for signs of streamer evolution preferentially on >one polarity. That be the negative polarity ;-)) Bandwidth is a problem. I can go to 40MHz on the streamer current and 20MHz on I base. I hope Ibase is well and fine. But I worry if 40MHz is good enough for Istreamer... Maybe HP has higher speed optics now... Doubtful, since Carly has totally nuked the HP place >:-(( Maybe the Chinese have a higher-performance replacement... > >Either way, tons of stuff to go at. Oh!! You think secondaries were fun!!! Steamers... we're talking fire now!!!!!!! :o))))))))) Cheers, Terry >-- >Paul Nicholson >-- > Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Fri, 6 Sep 2002 08:34:36 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Fri, 06 Sep 2002 08:18:36 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: Re: OLTC update - primary IGBT loss X-Mailing-List: archive/latest/2171 X-Loop: tesla@pupman.com Original poster: "Paul Nicholson by way of Terry Fritz " Terry wrote: > As it turns out, I apparently do not need more top capacitance but > rather more inductance for higher Q and better streamer power > transfer. I think that such a conclusion may be premature, although not necessarily wrong. Perhaps you should hold off committing to a new secondary until after a closer look at the breakout behaviour of the present coil. It may be that during closer investigation it will become clear that either you are running short of charge, or have insufficient topvolts. I think we understand the linear response of your coil, but we've a lot more info to wring out of its interaction with the load. > Bandwidth is a problem. I can go to > 40MHz on the streamer current and 20MHz on I base. That ought to do for a start. We'll notice if substantial components lie above the probe cutoff because when we calculate streamer dissipation from the measured current, it will fall short of the amount required to reproduce the observed ringdown. Hmm, that statement assumes the streamer load is a significant part of the total dissipation, which may not be the case (: > It appears that the SonoTube will not be transmuted into gold > bullion from this exercise ;-)) I don't think we've unequivocally established that sonotube is lossy, although it certainly has given us cause for suspicion. In this case I think that proximity effect is the main culprit. > So I ordered up some threaded brass balls from MSC. 1, 1+3/8, and > 1+7/8 inch diameter. Those put us in the right ballpark for breakout at voltages in reach of your Jennings probe. Once you've settled on a terminal geometry, let me know and I'll try to predict the firing voltage at which breakout should start. -- Paul Nicholson -- Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Sat, 7 Sep 2002 22:11:44 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Sat, 07 Sep 2002 22:03:51 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: Re: OLTC update - primary IGBT loss - triple primary X-Mailing-List: archive/latest/2300 X-Loop: tesla@pupman.com Original poster: "by way of Terry Fritz " I'm not sure about this but what about in the software, having three seperate transformers, with the primaries in paralell and the secondaries in series? Just wondering what that would do, Jonathon > > I'm having trouble modeling your triple parallel turn primary - the > interaction between the three is not modeled by the tssp software and > they are too far apart to model as a single turn. This is why I > haven't sent any V/I profiles. Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Wed, 21 Aug 2002 21:01:58 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Wed, 21 Aug 2002 20:58:16 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: OLTC update - Primary inductor voltage spike X-Mailing-List: archive/latest/1378 X-Loop: tesla@pupman.com Original poster: "Terry Fritz" Hi All, Tonight I have been working on a current glitch problem. Since I can quench the IGBT array spark gap at any time. I can pick some really "bad" times. In this circuit: http://hot-streamer.com/temp/OLTC08-21-01.gif Consider the instant in time of the primary circuit ringdown when the voltage on the cap is zero but the current is say 2000 amps through the inductor. If we open the switch right then, the inductive kick off the primary will cause a voltage spike. http://hot-streamer.com/temp/OLTC08-21-02.gif http://hot-streamer.com/temp/OLTC08-21-03.gif No problem in the negative direction since the anti-parallel diode will catch it (which it does perfectly). However, in the positive direction, there is nothing to stop the voltage spike except the IGBT breakdown and the MOVs. But the MOVs are too slow :-( But I think TVS transient absorbers will work. I stung some odd valued ones together and they seem to hit the spike very hard. http://hot-streamer.com/temp/OLTC08-21-04.gif http://hot-streamer.com/temp/OLTC08-21-05.gif So I'll order up the right values from DigiKey and that should take care of it. The energy of the spike is not very great so should work fine. "Normally" this is not a big problem, but the coil should be able to handle any adjustment of the gap dwell time without worry. I ran a bunch of models and tests looking for such odd glitches and turn on/off transients but everything else looks perfectly fine. So the primary circuit appears to be all done and working. I am going to run it off 120VAC at first with a 20 ohm power resitor in the charging circuit. This will limit the IGBT current to a nice safe level. I seem to have far more power available than I know what to do with ;-) I worked so hard getting power into the coil... Now I am try to find ways of getting rid of power :o)) Cheers, Terry Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Wed, 21 Aug 2002 22:46:13 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Wed, 21 Aug 2002 22:40:25 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: Re: OLTC update - Primary inductor voltage spike X-Mailing-List: archive/latest/1380 X-Loop: tesla@pupman.com Original poster: "Eddie Burwell by way of Terry Fritz " How about a simple circuit that latches the gate on and can only be reset when the anti parallel diodes are conducting? Or perhapse a circuit that prohibits turn off if the IGBT has a forward voltage drop. Eddie Burwell Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Fri, 23 Aug 2002 19:25:36 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Fri, 23 Aug 2002 17:05:31 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: OLTC update - Primary inductor voltage spike X-Mailing-List: archive/latest/1452 X-Loop: tesla@pupman.com Original poster: "Terry Fritz" Hi All, Just to update... I overnighted some 150 volt transorbs in from DigiKey (I "needed" them before the weekend...) I am happy to report they work perfectly to stop the high voltage inductive kicks of the OLTC's primary if one sets the timing wrong. http://hot-streamer.com/temp/OLTC08-23-01.jpg http://hot-streamer.com/temp/OLTC08-23-02.gif So just a few 30 cent parts (MUCH more $$ overnight ;-)) fixes the problem :-))) For the record, they are DigiKey # 1.5KE150CADICT-ND Cheers, Terry ============== Hi All, Tonight I have been working on a current glitch problem. Since I can quench the IGBT array spark gap at any time. I can pick some really "bad" times. In this circuit: http://hot-streamer.com/temp/OLTC08-21-01.gif Consider the instant in time of the primary circuit ringdown when the voltage on the cap is zero but the current is say 2000 amps through the inductor. If we open the switch right then, the inductive kick off the primary will cause a voltage spike. http://hot-streamer.com/temp/OLTC08-21-02.gif http://hot-streamer.com/temp/OLTC08-21-03.gif No problem in the negative direction since the anti-parallel diode will catch it (which it does perfectly). However, in the positive direction, there is nothing to stop the voltage spike except the IGBT breakdown and the MOVs. But the MOVs are too slow :-( But I think TVS transient absorbers will work. I stung some odd valued ones together and they seem to hit the spike very hard. http://hot-streamer.com/temp/OLTC08-21-04.gif http://hot-streamer.com/temp/OLTC08-21-05.gif So I'll order up the right values from DigiKey and that should take care of it. The energy of the spike is not very great so should work fine. "Normally" this is not a big problem, but the coil should be able to handle any adjustment of the gap dwell time without worry. I ran a bunch of models and tests looking for such odd glitches and turn on/off transients but everything else looks perfectly fine. So the primary circuit appears to be all done and working. I am going to run it off 120VAC at first with a 20 ohm power resitor in the charging circuit. This will limit the IGBT current to a nice safe level. I seem to have far more power available than I know what to do with ;-) I worked so hard getting power into the coil... Now I am try to find ways of getting rid of power :o)) Cheers, Terry Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Mon, 26 Aug 2002 01:26:54 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Mon, 26 Aug 2002 01:24:32 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: OLTC Update - The baby has arrived :-))) X-Mailing-List: archive/latest/1533 X-Loop: tesla@pupman.com Original poster: "Terry Fritz" Hi All, Our local Tesla meet was tonight and I barely got everything together and thrown into the car to Denver. Lots of last minute stuff... I got some thick poly sheet on the way since primary to secondary arcs were a problem yesterday. On the way down, I decided to run it till it explodes :o)) So we got there and set it up in Bill's lab: http://hot-streamer.com/temp/OLTC08-25-01.jpg Note the poly sheet and raising the secondary modifications. This was after the primary to secondary arcing punched a hole clean through a sheet of 3/16" G-10 (brand new too!). The dielectric properties of G-10 allowed enough leakage current to carbonize a path "through" the G-10. The many layers of poly act like many caps in series so there is very little leakage current. A great trick!! After these mods, the coil worked perfectly with no arcs. I think the coupling neared the optimal 0.095 for this coil. I was a little worried since reviewing the flight tape yesterday suggested that the coil was damaged buy the "odd sound". The output decrease instantly with the sound. As it turned out, it was just corona spraying on the back side of the coil. There was no damage after all ;-)) That shrink wrap is wonderful stuff!! What IS that stuff anyway?? Earlier in the day, I had added a cap to my Tesla Coil Tuner (TCT) so it could work with a low frequency coil like this and calibrated it with the frequency counter function of the HP meter. I could simply tune the coil by raising or lowering the toroid on the brass all-thread rod. So I tuned the secondary about 5% low, which as I write this, I realize was incorrect =:O Arauugh!!!! Should have been 5% high and the streamers would have brought it down... So the darn thing was about 10% out of tune >:-P So we ran it off the variac slowly adding more and more power. It easily lit all the florescent lights in the room as shown here: http://hot-streamer.com/temp/OLTC08-25-05.jpg Soon, I had weaned it from the variac (and high power limiting resistor) and it was running in it's full "low power" mode! It was now a true transformerless Tesla coil running as a 35 pound unit. The controllers and all worked perfectly! The IGBTs were running at about 2500 amps. Here is the schematic of the system: http://hot-streamer.com/temp/OLTC08-25-02.gif The sparks were a little short: http://hot-streamer.com/temp/OLTC08-25-03.jpg But there were sparks and a heck of a lot of "power" that filled the room. I could kick myself now for screwing up the tuning thing but... The heck with it ;-)) The power of the coil was "ferocious". None of the usual "let me touch it" folks wanted to go near it :o))) http://hot-streamer.com/temp/OLTC08-25-02.jpg It was like burning the aluminum tape off and pitting the aluminum toroid :-)) Seemed to have low voltage, but very high current, arcs. I thought I may have messed up the coil's output impedance, but now I think it was 10% out of tune :-p Here is some testing at full power (still, just off the weenie 120VAC...) http://hot-streamer.com/temp/OLTC08-25-06.jpg This is after we had optimized the dwell time with a wooden stick attached to the controller dial. It was really cool and had a giant blue glow that the picture didn't capture well. The arcs were about a foot and a half. The dwell time was only 45uS and the arcs seemed "short", but with my darn tuning error... Here we are frying a Microsoft CD :-)) http://hot-streamer.com/temp/OLTC08-25-04.jpg So there was a bad tuning error but all else went just fine. The controller did perfectly. The IGBTs ran at 2500 amps just fine. Messing around with the dwell and all proved that the transorbes and all the protection circuits work just fine. Everything came home alive and well :-)) If wee "could" have blow the electronics, they "would" have blown... Sorry Marco, my dead IGBT bucket is still empty :o))) Bill did not have 240VAC available (probably a good thing :o)) but at 120VAC the OLTC seemed to run just fine. Much to ponder... But not as much as it "could" have been :o))) So, now, there is now doubt, the OLTC is born!!! :-)))))) Cheers, Terry Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Mon, 26 Aug 2002 08:21:22 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Mon, 26 Aug 2002 08:04:00 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: Re: OLTC Update - The baby has arrived :-))) X-Mailing-List: archive/latest/1534 X-Loop: tesla@pupman.com Original poster: "Kevin Ottalini by way of Terry Fritz " Congratulations Terry! A lot of hard work and skull scratching has really paid off, Yea! Kevin > > So, now, there is now doubt, the OLTC is born!!! :-)))))) > > Cheers, > > Terry > > > > > Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Mon, 26 Aug 2002 08:22:57 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Mon, 26 Aug 2002 08:04:25 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: RE: OLTC Update - The baby has arrived :-))) X-Mailing-List: archive/latest/1536 X-Loop: tesla@pupman.com Original poster: "by way of Terry Fritz " Hi Terry, > Original poster: "Terry Fritz" > So there was a bad tuning error but all else went just fine. The > controller did perfectly. The IGBTs ran at 2500 amps just > fine. Messing > around with the dwell and all proved that the transorbes and all the > protection circuits work just fine. Everything came home > alive and well > :-)) If wee "could" have blow the electronics, they "would" > have blown... > Sorry Marco, my dead IGBT bucket is still empty :o))) Congratulations, well done! I guess now what the list is waiting for is one of your nice and tidy Word documents with all the instructions for building the OLTC. When do you think you can post the *complete* schematics of the OLTC? Could you also "scope-around" the circuit when the streamers are hitting ground? In particular, I would like the see the IGBT Vge and Vce waveforms at full-power. You did it, Terry! Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Mon, 26 Aug 2002 08:11:53 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Mon, 26 Aug 2002 08:04:37 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: Re: OLTC Update - The baby has arrived :-))) X-Mailing-List: archive/latest/1535 X-Loop: tesla@pupman.com Original poster: "tesla by way of Terry Fritz " Congratulations Terry Been a good serial as it were.Tnx for sharing it, your willingness to do this has added much enjoyment to the hobby. See Below, have you just invented a perfect Magnifier driver ? Best Ted L in NZ > It was like burning the aluminum tape off and pitting the aluminum toroid > :-)) Seemed to have low voltage, but very high current, arcs. Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Mon, 26 Aug 2002 08:22:57 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Mon, 26 Aug 2002 08:05:25 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: Re: OLTC Update - The baby has arrived :-))) X-Mailing-List: archive/latest/1542 X-Loop: tesla@pupman.com Original poster: "Brian by way of Terry Fritz " AWESOME! cul brian f. ----- Original Message ----- From: "Tesla list" To: Sent: Monday, August 26, 2002 3:24 AM Subject: OLTC Update - The baby has arrived :-))) > Original poster: "Terry Fritz" > > Hi All, > > Our local Tesla meet was tonight and I barely got everything together and > thrown into the car to Denver. Lots of last minute stuff... I got some > thick poly sheet on the way since primary to secondary arcs were a problem > yesterday. On the way down, I decided to run it till it explodes :o)) > > So we got there and set it up in Bill's lab: > > http://hot-streamer.com/temp/OLTC08-25-01.jpg > > Note the poly sheet and raising the secondary modifications. This was > after the primary to secondary arcing punched a hole clean through a sheet > of 3/16" G-10 (brand new too!). The dielectric properties of G-10 allowed > enough leakage current to carbonize a path "through" the G-10. The many > layers of poly act like many caps in series so there is very little leakage > current. A great trick!! After these mods, the coil worked perfectly with > no arcs. I think the coupling neared the optimal 0.095 for this coil. > > I was a little worried since reviewing the flight tape yesterday suggested > that the coil was damaged buy the "odd sound". The output decrease > instantly with the sound. As it turned out, it was just corona spraying on > the back side of the coil. There was no damage after all ;-)) That shrink > wrap is wonderful stuff!! What IS that stuff anyway?? > > Earlier in the day, I had added a cap to my Tesla Coil Tuner (TCT) so it > could work with a low frequency coil like this and calibrated it with the > frequency counter function of the HP meter. I could simply tune the coil > by raising or lowering the toroid on the brass all-thread rod. So I tuned > the secondary about 5% low, which as I write this, I realize was incorrect > =:O Arauugh!!!! Should have been 5% high and the streamers would have > brought it down... So the darn thing was about 10% out of tune >:-P > > > So we ran it off the variac slowly adding more and more power. It easily > lit all the florescent lights in the room as shown here: > > http://hot-streamer.com/temp/OLTC08-25-05.jpg > > Soon, I had weaned it from the variac (and high power limiting resistor) > and it was running in it's full "low power" mode! It was now a true > transformerless Tesla coil running as a 35 pound unit. The controllers and > all worked perfectly! The IGBTs were running at about 2500 amps. > > Here is the schematic of the system: > > http://hot-streamer.com/temp/OLTC08-25-02.gif > > The sparks were a little short: > > http://hot-streamer.com/temp/OLTC08-25-03.jpg > > But there were sparks and a heck of a lot of "power" that filled the room. > I could kick myself now for screwing up the tuning thing but... The heck > with it ;-)) > > The power of the coil was "ferocious". None of the usual "let me touch it" > folks wanted to go near it :o))) > > http://hot-streamer.com/temp/OLTC08-25-02.jpg > > It was like burning the aluminum tape off and pitting the aluminum toroid > :-)) Seemed to have low voltage, but very high current, arcs. I thought I > may have messed up the coil's output impedance, but now I think it was 10% > out of tune :-p > > Here is some testing at full power (still, just off the weenie 120VAC...) > > http://hot-streamer.com/temp/OLTC08-25-06.jpg > > This is after we had optimized the dwell time with a wooden stick attached > to the controller dial. It was really cool and had a giant blue glow that > the picture didn't capture well. The arcs were about a foot and a half. > The dwell time was only 45uS and the arcs seemed "short", but with my darn > tuning error... > > Here we are frying a Microsoft CD :-)) > > http://hot-streamer.com/temp/OLTC08-25-04.jpg > > So there was a bad tuning error but all else went just fine. The > controller did perfectly. The IGBTs ran at 2500 amps just fine. Messing > around with the dwell and all proved that the transorbes and all the > protection circuits work just fine. Everything came home alive and well > :-)) If wee "could" have blow the electronics, they "would" have blown... > Sorry Marco, my dead IGBT bucket is still empty :o))) Bill did not have > 240VAC available (probably a good thing :o)) but at 120VAC the OLTC seemed > to run just fine. > > Much to ponder... But not as much as it "could" have been :o))) > > So, now, there is now doubt, the OLTC is born!!! :-)))))) > > Cheers, > > Terry > > > > Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Mon, 26 Aug 2002 08:15:10 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Mon, 26 Aug 2002 08:06:57 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: Re: OLTC Update - The baby has arrived :-))) X-Mailing-List: archive/latest/1547 X-Loop: tesla@pupman.com Original poster: "G by way of Terry Fritz " Your results are wonderful. Now we know the models have been truely borne out in the real world. Perhaps today the future has arrived? Thank you, Terry! Gregory >So, now, there is now doubt, the OLTC is born!!! :-)))))) > >Cheers, > > Terry -- "Without ZIM, I am lost." GeekID#-1229 http://thegeekgroup.org Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Mon, 26 Aug 2002 12:29:53 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Mon, 26 Aug 2002 12:19:25 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: Re: OLTC Update - The baby has arrived :-))) X-Mailing-List: archive/latest/1550 X-Loop: tesla@pupman.com Original poster: "Mark W. Stolz by way of Terry Fritz " Terry Congratulations! I guess we know how the cigars will get lit. ;-) Mark Stolz Houston, TX > >Original poster: "Terry Fritz" > >Hi All, > >So, now, there is now doubt, the OLTC is born!!! :-)))))) > >Cheers, > > Terry > > > _________________________________________________________________ Join the world’s largest e-mail service with MSN Hotmail. http://www.hotmail.com Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Mon, 26 Aug 2002 12:37:01 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Mon, 26 Aug 2002 12:19:59 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: Re: OLTC Update - The baby has arrived :-))) X-Mailing-List: archive/latest/1552 X-Loop: tesla@pupman.com Original poster: "S Gaeta by way of Terry Fritz " Congratulations Terry! Instead of passing out cigars to all 800 or so of us, you can just burn one up on the torroid, and post a pic. With proper tuning, I am sure that we will see dramatic improvements. Sue Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Mon, 26 Aug 2002 12:38:19 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Mon, 26 Aug 2002 12:25:06 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: Re: OLTC Update - The baby has arrived :-))) X-Mailing-List: archive/latest/1560 X-Loop: tesla@pupman.com Original poster: "K. C. Herrick by way of Terry Fritz " I'll add my congratulations to the rest! Good work, Terry. One thing that surprises me, not having to do with the primary scheme at all, is the spacing you have between the top of the coil and the toroid. I would have thought that the field of the toroid, "protecting", so to speak, the top of the coil, would not extend that far. I'd expect sparks from the top of the coil. Let me remark that your work with the OLTC has inspired me to consider a lower-resistance configuration in my s.s. system, in order to improve the amperes-x-turns factor toward what you have achieved--and to bring it closer to what I had had in mind in the first place. After all, it's ampere-turns that do the job in the primary, isn't that right? I'll post something shortly for those interested in a possible adaptation of your fundamental notion--low voltage applied to a very-low-impedance primary coil--incorporating my current s.s. scheme. Jimmy Hynes' comment about "k" is interesting: I see nothing except dielectric breakdown that would preclude making k as high as possible, in a s.s. system, as long as the driving transistors are protected against voltage transients. (I'll try to work on that...) Ken Herrick Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Mon, 26 Aug 2002 12:49:08 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Mon, 26 Aug 2002 12:46:10 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: Re: OLTC Update - The baby has arrived :-))) X-Mailing-List: archive/latest/1563 X-Loop: tesla@pupman.com Original poster: "Terry Fritz" At 10:42 AM 8/26/2002 -0700, you wrote: >I'll add my congratulations to the rest! Good work, Terry. Thanks to you and everyone :-))) > >One thing that surprises me, not having to do with the primary scheme at >all, is the spacing you have between the top of the coil and the toroid. >I would have thought that the field of the toroid, "protecting", so to >speak, the top of the coil, would not extend that far. I'd expect sparks >from the top of the coil. I am raising and lowering the toroid for tuning. It just ended up way up there. Not much thought went into anything else ;-) > >Let me remark that your work with the OLTC has inspired me to consider a >lower-resistance configuration in my s.s. system, in order to improve the >amperes-x-turns factor toward what you have achieved--and to bring it >closer to what I had had in mind in the first place. After all, it's >ampere-turns that do the job in the primary, isn't that right? I'll post >something shortly for those interested in a possible adaptation of your >fundamental notion--low voltage applied to a very-low-impedance primary >coil--incorporating my current s.s. scheme. Neat! > >Jimmy Hynes' comment about "k" is interesting: I see nothing except >dielectric breakdown that would preclude making k as high as possible, in >a s.s. system, as long as the driving transistors are protected against >voltage transients. (I'll try to work on that...) > Those TVS transorbes from DigiKey work great! Cheers, Terry >Ken Herrick > Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Fri, 23 Aug 2002 06:35:31 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Thu, 22 Aug 2002 23:53:16 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: OLTC update - winding the secondary X-Mailing-List: archive/latest/1436 X-Loop: tesla@pupman.com Original poster: "Terry Fritz" Hi All, For the OLTC effort, I have to wind like a mile and a half of wire on a secondary. I went and got like $10 worth of stuff for this; http://hot-streamer.com/temp/OLTC08-22-04.jpg http://hot-streamer.com/temp/OLTC08-22-05.jpg http://hot-streamer.com/temp/OLTC08-22-05.jpg Seems to test out fine. The drill easily stops if the torque incresses so no borken wires. The variac controls the speed of the drill just fine. I think this will work well. Cheers, Terry Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Fri, 23 Aug 2002 08:09:08 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Fri, 23 Aug 2002 08:04:42 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: RE: OLTC update - winding the secondary X-Mailing-List: archive/latest/1445 X-Loop: tesla@pupman.com Original poster: "Lau, Gary by way of Terry Fritz " I used a very similar jig, also with VSR drill and Variac. The problem I had was finding a support "bearing" for the threaded rod to pass through that doesn't engage the threads. Regards, Gary Lau MA, USA -----Original Message----- From: Tesla list [mailto:tesla@pupman.com] Sent: Friday, August 23, 2002 1:53 AM To: tesla@pupman.com Subject: OLTC update - winding the secondary Original poster: "Terry Fritz" Hi All, For the OLTC effort, I have to wind like a mile and a half of wire on a secondary. I went and got like $10 worth of stuff for this; http://hot-streamer.com/temp/OLTC08-22-04.jpg http://hot-streamer.com/temp/OLTC08-22-05.jpg http://hot-streamer.com/temp/OLTC08-22-05.jpg Seems to test out fine. The drill easily stops if the torque incresses so no borken wires. The variac controls the speed of the drill just fine. I think this will work well. Cheers, Terry Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Fri, 23 Aug 2002 08:09:20 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Fri, 23 Aug 2002 08:04:47 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: Re: OLTC update - winding the secondary X-Mailing-List: archive/latest/1443 X-Loop: tesla@pupman.com Original poster: "tesla by way of Terry Fritz " Hi Terry Tried the gravity tensioner trick for wire Pass wire thru medium weighted object between spool and form. keeps constant tension as long as weight does not hit gnd. I use cotton tied to the weight to keep it form moving along the wire too far. Done well this trick saves lots of effort keeping tension on feed to coil Best Ted L > Hi All, > > For the OLTC effort, I have to wind like a mile and a half of wire on a > secondary. > > I went and got like $10 worth of stuff for this; Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Fri, 23 Aug 2002 19:20:08 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Fri, 23 Aug 2002 11:07:58 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: Re: OLTC update - winding the secondary X-Mailing-List: archive/latest/1450 X-Loop: tesla@pupman.com Original poster: "Jim Lux by way of Terry Fritz " Standard two bolt pillow blocks work well.. Tesla list wrote: > > Original poster: "Lau, Gary by way of Terry Fritz " > > I used a very similar jig, also with VSR drill and Variac. The problem I > had was finding a support "bearing" for the threaded rod to pass through > that doesn't engage the threads. > > Regards, Gary Lau > MA, USA > Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Fri, 23 Aug 2002 20:23:07 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Fri, 23 Aug 2002 20:16:58 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: Re: OLTC update - winding the secondary X-Mailing-List: archive/latest/1458 X-Loop: tesla@pupman.com Original poster: "Brian by way of Terry Fritz " hi, might want to use a piece of cloth pinched with a clothespin for a wire tensioner. I use that and a little drag on the wire coil so it wont birdcage. I birdcaged a 5 lb roll of #46 wire, after that the longest piece you could get off the roll was 6 inches. I threw it into a hot fire in the fireplace and it made nice colored flames and burned up et. all. cul brian f. ----- Original Message ----- From: "Tesla list" To: Sent: Friday, August 23, 2002 1:53 AM Subject: OLTC update - winding the secondary > Original poster: "Terry Fritz" > > Hi All, > > For the OLTC effort, I have to wind like a mile and a half of wire on a > secondary. > > I went and got like $10 worth of stuff for this; > > http://hot-streamer.com/temp/OLTC08-22-04.jpg > > http://hot-streamer.com/temp/OLTC08-22-05.jpg > > http://hot-streamer.com/temp/OLTC08-22-05.jpg > > Seems to test out fine. The drill easily stops if the torque incresses so > no borken wires. The variac controls the speed of the drill just fine. I > think this will work well. > > Cheers, > > Terry > > > > Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Sun, 11 Aug 2002 10:51:46 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Sun, 11 Aug 2002 10:36:42 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: [Fwd: OLTC update] X-Mailing-List: archive/latest/752 X-Loop: tesla@pupman.com Original poster: "David Sharpe by way of Terry Fritz " Terry wanted me to forward this to the list while he is sleeping... The OLTC thing is getting bigger...MUCH BIGGER, then anyone would have predicted. Like dynamic tuning by controlling how many IGBT's are switching (controling the tank C). Would now require the CEEC structure I mentioned in a previous post to allow bidirectional isolation. The IGBT / capacitor structures can now be modularized for plug in into busbars from primaries, which is exactly the same design feature used on high power Klystron drivers for linear accelerators. Another point is potentially (no pun) scale up to truly enormous power capabilities. Now if we could just get the voltages up, so we could reduce tank losses (i^2r and proximity)... Best Regards Dave Sharpe, TCBOR Chesterfield, VA. USA Return-Path: Received: from mx05.mrf.mail.rcn.net ([207.172.4.54] [207.172.4.54]) by mta04.mrf.mail.rcn.net with ESMTP id <20020811044326.ULHU385.mta04.mrf.mail.rcn.net@mx05.mrf.mail.rcn.net>; Sun, 11 Aug 2002 00:43:26 -0400 Received: from dnvrpop8.dnvr.uswest.net ([206.196.128.10]) by mx05.mrf.mail.rcn.net with smtp (Exim 3.35 #6) id 17dkZe-0002qO-00 for sccr4us@erols.com; Sun, 11 Aug 2002 00:43:30 -0400 Received: (qmail 70696 invoked by uid 0); 11 Aug 2002 04:43:26 -0000 Received: from unknown (HELO 2x400mhz) (63.229.238.61) by dnvrpop8.dnvr.uswest.net with SMTP; 11 Aug 2002 04:43:26 -0000 Date: Sat, 10 Aug 2002 22:43:49 -0600 Message-Id: <4.1.20020810222127.00a23fc8@pop.dnvr.qwest.net> From: "Terry Fritz" To: "David Sharpe" Approved: twftesla@qwest.net X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: Re: OLTC update In-Reply-To: <3D55E0C2.32751EEC@erols.com> References: <4.1.20020810212426.00a1da80@pop.dnvr.qwest.net> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" X-Mozilla-Status2: 00000000 Hi Dave, At 11:57 PM 8/10/2002 -0400, you wrote: >Terry > >AWESOME!!! You just made a self ballasted current source >where the currents are dependent on the statistical manufacturing >tolerances on capacitor values. What modeling I've done suggests >that 5% tolerance are acutally within 1% when taken as a grand >average. Need to scale up or drop frequency lower (or dynamically >tune the system!!!! :^) ) Adjust the number of active IGBT's on >the fly. You're right, I'm crying with you. :^) Oh God!!! Your right, you can tune the darn thing too by just "selecting" cap strings!!!!!!!!!! Also, there is no limit to the number of IGBTs in this method. So a 300uF, or whatever cap, with a big number of IGBTs is practical!!! What!!! Like 50,000 amp primaries :-))))) Suddenly, there is no limit to the power... :o))))))))))))) We could scale it up till the breaker box blows off the wall :-))))))) > >BTW this concept is similarly used with inductors to tie together >very large bridge converters for large (100kW to 1MW+) SS Induction >heating appartus. Lumped inductors in load then become part of >total tank circuit, and FORCE current sharing similarly to caps in >this application. I can find URL with this application in it to illustrate >my point... Yep! It's not a new concept. I have used it to do current measurements on MMCs when I didn't have the ability to measure the full current. I just did one string... > >Excellent, now sleep on it, but I wanna see it FIRE!!! Yep!! I sleep a lot, but still not enough to handle all this :-))) I "thought" this may be "cool", but I never knew it was a "big thing" ;-)) Think we can obsolete variacs and transformers (NSTs, MOTs, and even PIGs) like we did them oil filled homemade poly caps :-))) Cheers, Terry > >Regards >Dave Sharpe, TCBOR >Chesterfield, VA. USA Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Mon, 12 Aug 2002 18:31:15 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Mon, 12 Aug 2002 18:17:41 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: Re: [Fwd: OLTC update] X-Mailing-List: archive/latest/871 X-Loop: tesla@pupman.com Original poster: "by way of Terry Fritz " I think this is extremely awsome! I am watching, right in front of me, the development of a new breed of tesla coil !!! (tesla would be proud :-)) ) I (and probly many others) wish I (we) could be a part of this, but my (our) electrical expereience/knowledge is not adequate. Oh well, I was on the same mailing list as those famous people!! :-D) Terry, others, If your name(s) weren't in the books before, they are now..... ----------------------- I think the Geek group has an opertunity here with the IGBTs (what does that stand for anyways? I think it would be nice if one of the people who know all about OLTC would post an informative email about how it works... and such... (www.oltc.com is not yet taken!!)) just like they did with the CD942's caps..... Peace, and good luck --------------------------------------- Jonathon Reinhart hot-streamer.com/jonathon Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Wed, 21 Aug 2002 12:17:39 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Wed, 21 Aug 2002 12:10:41 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: OLTC'CEEC' IGBT Bidirectional Switch X-Mailing-List: archive/latest/1335 X-Loop: tesla@pupman.com Original poster: "David Sharpe by way of Terry Fritz " Terry, All I mentioned earlier that it would only be a matter of time before a 'C-E-E-C' matrix converter module would be available from suppliers. Check out attached URL's: http://www.powerpulse.net/cgi-bin/displayprod_new.pl?id=6349 This is announcement from PowerPulse.net concerning a new device from Dynex. http://www.dynexsemi.com/products/pdf/ds5524.pdf The Dynex part (DIM400PBM17-A000) is a +/- 1.7kV, 400A power block module (PBM) bidirectional switch designed for brushless motor controllers and matrix converters. AFAIK, this is the first commercial offering of a modular bidirectional controlled power switch. Pulse currents are quite impressive (>800A), as well as thermal power rating (3.4kW), and isolation voltage to a grounded heatsink (4.0kV). I wonder if our UK counterparts could determine availability and pricing?? Probably WAY too "rich" for my (our) pocketbook(s)... :^C ; but the "correct" way to go for high power industrial type applications. My guess is cost will probably be in the $1,500-3,000 US range each. But we are talking REAL parts here, not "vapourware"... :^). http://www.dynexsemi.com/products/appnotes/data/an4504.pdf This is an application note from Dynex covering typical manufacturer specifications for high power IGBT's, generic stuff typical for IR or other manufacturers. The specification of "Peak Pulse Power Ratings" is not listed due to obvious circuit/design variances that can lead to device destruction, even when not intended. Based on all data I've seen , IGBT's are generically capable of 2X Ic continuous on a pulse power basis, and N channel Power MOSFET's (enhancement) are capable of up to 4X pulse power rating (with restrictions). More food for thought... Regards Dave Sharpe, TCBOR Chesterfield, VA. USA Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Wed, 14 Aug 2002 22:00:07 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Wed, 14 Aug 2002 21:54:01 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: OLTC-Inductors X-Mailing-List: archive/latest/1029 X-Loop: tesla@pupman.com Original poster: "Terry Fritz" Hi All, I have been working on the inductors for the OLTC tonight. Actually, just thinking about them... The "specs" are: 1. Easy to make and reproducible by your average coiler (or easy to just buy out right). 2. Light weight since this coil is "hoot'n and toot'n" about no heavy "big iron" stuff in it. 3. Can reasonably handle the voltages and currents shown (note that the current is 100X in the pic): http://hot-streamer.com/temp/OLTC8-14-03.gif About 5.5 amps peak and 650 volts peak. 3. The FT looks like this: http://hot-streamer.com/temp/OLTC8-14-04.gif Looks like all 100Hz to 1kz stuff. 4. There are two inductors at 75mH each. They could probably be on the same core in some common mode if that would make things easier. Here is the system schematic (Lb1, Lb2): http://hot-streamer.com/temp/OLTC8-14-02.gif 5. Not too expensive, but realizing this is probably like a $500 class coil... If anyone has any ideas here they are very welcome :-)) Either on list or direct to: terrellf@qwest.net I guess it could be one 150mH inductor, but the filtering and "balance" seems more natural with two inductors. Cheers, Terry Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Thu, 15 Aug 2002 23:39:22 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Thu, 15 Aug 2002 23:32:11 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: OLTC-Inductors X-Mailing-List: archive/latest/1076 X-Loop: tesla@pupman.com Original poster: "Terry Fritz" Hi All, Well, I guess I should have known I was in trouble when I got zero response to this one :-)) I dumpster dived for some inductor cores today and found and made up this fancy 75mH choke: http://hot-streamer.com/temp/OLTC8150011.jpg but it saturated in testing: http://hot-streamer.com/temp/OLTC8-15-02.gif Oh oh.. That amps per turn stuff... I ain't no golly darn transformer design genius... I played with some transformers and such but saturation is a BIG issue! I took an old core from a variac and sliced it with a little finger nail file... Hahaha!! I used a cobalt alloy M42 hacksaw for cutting mil grade 6-4 titanium :o)) Cut it like butter... http://hot-streamer.com/temp/OLTC8150009.jpg It solved the saturation and gave ideal inductor responses: http://hot-streamer.com/temp/OLTC8-15-01.gif But it only measured 47mH.... So, to make a long day's story short, the resonant charging inductor is a big issue!!... I think it has to work at 120Hz (helps a LOT! as opposed to 60Hz...) Saturation is a killer. Probably going to need some "big iron" cores here! Not to bad really, but I thought this would be a trivial part... I don't think an air core inductor would work given the low (5 ohms) resistance needed. The Devil is in the details... Cheers, Terry >Hi All, > >I have been working on the inductors for the OLTC tonight. Actually, just >thinking about them... The "specs" are: > >1. Easy to make and reproducible by your average coiler (or easy to just >buy out right). > >2. Light weight since this coil is "hoot'n and toot'n" about no heavy "big >iron" stuff in it. > >3. Can reasonably handle the voltages and currents shown (note that the >current is 100X in the pic): > >http://hot-streamer.com/temp/OLTC8-14-03.gif > >About 5.5 amps peak and 650 volts peak. > >3. The FT looks like this: > >http://hot-streamer.com/temp/OLTC8-14-04.gif > >Looks like all 100Hz to 1kz stuff. > >4. There are two inductors at 75mH each. They could probably be on the >same core in some common mode if that would make things easier. > >Here is the system schematic (Lb1, Lb2): > >http://hot-streamer.com/temp/OLTC8-14-02.gif > >5. Not too expensive, but realizing this is probably like a $500 class coil... > >If anyone has any ideas here they are very welcome :-)) Either on list or >direct to: > >terrellf@qwest.net > >I guess it could be one 150mH inductor, but the filtering and "balance" >seems more natural with two inductors. > >Cheers, > > Terry > Delivered-To: terrellf@mail-dnvr.uswest.net Resent-Date: Sun, 18 Aug 2002 16:09:51 -0600 Resent-From: tesla@pupman.com Resent-Sender: tesla-request@pupman.com Date: Sun, 18 Aug 2002 16:01:06 -0600 From: "Tesla list" To: tesla@pupman.com X-Sender: twftesla@pop.dnvr.qwest.net X-Mailer: QUALCOMM Windows Eudora Pro Version 4.1 Subject: Re: OLTC-Inductors X-Mailing-List: archive/latest/1250 X-Loop: tesla@pupman.com Original poster: "Malcolm Watts by way of Terry Fritz " Hi Terry, I began to try an idea a few years ago which you might be able to use: On 15 Aug 2002, at 23:32, Tesla list wrote: > Original poster: "Terry Fritz" > > Hi All, > > Well, I guess I should have known I was in trouble when I got zero response > to this one :-)) > > I dumpster dived for some inductor cores today and found and made up this > fancy 75mH choke: > > http://hot-streamer.com/temp/OLTC8150011.jpg > > but it saturated in testing: > > http://hot-streamer.com/temp/OLTC8-15-02.gif > > Oh oh.. That amps per turn stuff... I ain't no golly darn transformer > design genius... > > I played with some transformers and such but saturation is a BIG issue! I > took an old core from a variac and sliced it with a little finger nail > file... Hahaha!! I used a cobalt alloy M42 hacksaw for cutting mil grade > 6-4 titanium :o)) Cut it like butter... > > http://hot-streamer.com/temp/OLTC8150009.jpg > > It solved the saturation and gave ideal inductor responses: > > http://hot-streamer.com/temp/OLTC8-15-01.gif > > But it only measured 47mH.... > > So, to make a long day's story short, the resonant charging inductor is a > big issue!!... I think it has to work at 120Hz (helps a LOT! as opposed to > 60Hz...) Saturation is a killer. Probably going to need some "big iron" > cores here! Not to bad really, but I thought this would be a trivial > part... I don't think an air core inductor would work given the low (5 > ohms) resistance needed. > > The Devil is in the details... > > Cheers, > > Terry I grabbed throw-out SMPS from anywhere I could get them, pulled all the *transformers* (NOT chokes) out, and smashed the cores up, finally stuffing the broken pieces into a PVC pipe. The material is N27/3C8 mostly and would work well up to 100kHz. It would make an ideal core for a high frequency choke. Adjustable too. Regards, malcolm